Article

Eveningness is related to men’s mating success

April 2012
Personality and Individual Differences 53(3):263-267

April 2012
53(3):263-267

DOI:10.1016/j.paid.2012.03.025

Authors:

Christoph Randler

University of Tuebingen

Show all 8 authorsHide

Men and women differ in sleep duration and timing of sleeping. Men sleep shorter and are later chronotypes, thus go to bed and get up later than women. This sexual dimorphism in chronotype is most striking between the beginning of puberty and beginning of menopause indicating the possibility of a sexually selected trait. Sleep duration, however, is different between the sexes already before and after the reproductive phase, suggesting a trait that is not under sexual section. In men, the most influential predictor of mating success was extraversion, followed by age, propensity to stay out late and evening orientation. This was confirmed by structural equation modeling showing both, an indirect and a direct fitness benefit of eveningness even when imposing extraversion and age as important predictor variables. As eveningness is related to an array of problematic behaviors, we suggest that it can be viewed as a kind of handicap.

Relationship between extraversion, propensity to stay out late and eveningness on mating success.

…

Figures - uploaded by Christian Vollmer

Content may be subject to copyright.

COVID-19 Pandemic on Fire: Evolved Propensities for Nocturnal Activities as a Liability Against Epidemiological Control

Article

Full-text available

Mar 2021

Humans have been using fire for hundreds of millennia, creating an ancestral expansion toward the nocturnal niche. The new adaptive challenges faced at night were recurrent enough to amplify existing psychological variation in our species. Night-time is dangerous and mysterious, so it selects for individuals with higher tendencies for paranoia, risk-taking, and sociability (because of security in numbers). During night-time, individuals are generally tired and show decreased self-control and increased impulsive behaviors. The lower visibility during night-time favors the partial concealment of identity and opens more opportunities for disinhibition of self-interested behaviors. Indeed, individuals with an evening-oriented chronotype are more paranoid, risk-taking, extraverted, impulsive, promiscuous, and have higher antisocial personality traits. However, under some circumstances, such as respiratory pandemics, the psychobehavioral traits favored by the nocturnal niche might be counter-productive, increasing contagion rates of a disease that can evade the behavioral immune system because its disease cues are often nonexistent or mild. The eveningness epidemiological liability hypothesis presented here suggests that during the COVID-19 pandemic, the evening-oriented psychobehavioral profile can have collectively harmful consequences: there is a clash of core tendencies between the nocturnal chronotype and the recent viral transmission-mitigating safety guidelines and rules. The pandemic safety protocols disrupt much normal social activity, particularly at night when making new social contacts is desired. The SARS-CoV-2 virus is contagious even in presymptomatic and asymptomatic individuals, which enables it to mostly evade our evolved contagious disease avoidance mechanisms. A growing body of research has indirectly shown that individual traits interfering with social distancing and anti-contagion measures are related to those of the nocturnal chronotype. Indeed, some of the social contexts that have been identified as superspreading events occur at night, such as in restaurants, bars, and nightclubs. Furthermore, nocturnal environmental conditions favor the survival of the SARS-CoV-2 virus much longer than daytime conditions. We compare the eveningness epidemiological liability hypothesis with other factors related to non-compliance with pandemic safety protocols, namely sex, age, and life history. Although there is not yet a direct link between the nocturnal chronotype and non-compliance with pandemic safety protocols, security measures and future empirical research should take this crucial evolutionary mismatch and adaptive metaproblem into account, and focus on how to avoid nocturnal individuals becoming superspreaders, offering secure alternatives for nocturnal social activities.

Chronotype dependent choosiness and mate choice

Article

Sep 2020
PERS INDIV DIFFER

Chronotype influences the success of mate choice. Evening types reproducibly report higher mating success than morning types. In this study, we directly assessed the reasons for these advantages, hypothesizing the degree of choosiness a person has concerning mate choice being causal. A total of N = 1247 (male = 440/female = 807) heterosexuals participated in an experiment. We defined two facets of choosiness: attractiveness rating and dating desire. Participants rated the attractiveness of opposite sex stimuli and indicated whether they had a desire to date the stimuli or not. Morningness in males correlated with a higher attractiveness-rating and dating desire, while results of evening-orientated males, and females in general were not significant. The causes of higher mating success in eveningness remains unclear. Unexpectedly, we showed that eveningness is related to a higher choosiness.

Reproductive Success, Relationship Orientation, and Sexual Behavior in Heterosexuals: Relationship With Chronotype, Sleep, and Sex

Article

Full-text available

Jul 2019

Following previous studies, chronotype was related to sexual attitudes and behavior. Evening people tend to be more promiscuous and follow short-term mating strategies and extra-pair matings (EPM), which might lead to a higher reproductive success. In this study, one aim was to assess reproductive success directly by asking for children, and, second, to obtain a higher sample size for the analysis of sexual behavior and chronotype than in previous studies. N ¼ 1,843 heterosexual persons (551 men, 1,288 women, 4 without data) responded to our online survey. Five hundred fifty-nine persons were single and 1,281 in a relationship; 203 reported having children (1.9 + 0.81). Age was positively related and age at first intercourse was negatively related to the number of children. People being later chronotypes had fewer children, and shorter sleep duration was linked with more children. Extroversion was correlated with number of children, as was the long-term relationship orientation. Sociosexual orientation and EPM were unrelated to number of children. Age at first intercourse was earlier in evening people, and unrestricted sociosexuality was higher in late chronotypes. Morning orientation correlated with long-term relationship orientation and eveningness with short-term relationship orientation. Number of sexual partners was lower in morning people. Men were more evening oriented, later chronotypes, and slept shorter. There were no differences in sociosexual behavior, but men were less restricted in attitude and desire. Men scored higher on short-term relationship orientation and women higher on long-term relationship orientation. This study confirmed previous results about chronotype and sexual behavior but provided the first evidence that morningness was related to higher reproductive success.

Sociosexuality, Morningness-Eveningness, and Sleep Duration

Article

Full-text available

Jan 2016

Morningness-eveningness is the preference for different times of day for activity and sleep. Here, we addressed the effects of sleep behaviour and morningness-eveningness on sociosexuality. Three hundred students (mean age 22.75 years, with 95% between 18 and 28) participated online, answering questions about morningness-eveningness (rMEQ), mid-point of sleep on free days (MSF), sleep duration, and the Sociosexuality Orientation Inventory–Revised (SOI-R). The SOI-R contains three subscales, Behavior, Attitude, and Desire. Evening orientation and short sleep duration were related to a higher total SOI-R and to the three subscales. Based on the linear models, the strongest effect on sociosexuality was produced by gender (27% explained variance) while age accounted for 6% of variance. Nonadditive variance explained by sleepwake behaviour was 7% (MSF), 4% (sleep duration), and 4% (rMEQ scores; 3% rMEQ-based typology). Older age was related to less restricted sociosexuality, and men were less restricted than women in Attitude and Desire. Sleep duration and rMEQ scores were associated with Attitude and Desire; but only MSF was significantly related to Behaviour. The data show that sleep-wake variables are associated with sociosexuality, with evening orientation and shorter sleep duration being related to a less restricted sociosexuality.

Morningness–eveningness and intrasexual competition in men

Article

Apr 2015
PERS INDIV DIFFER

A growing body of research points to a relationship between chronotype and socio-sexuality, especially in men, such that evening-types appear both to be more short-term mating oriented than morning-types and to possess more personality traits and other behavioral characteristics that facilitate sexual promiscuity. This study contributes to and expands this body of research by investigating the relationship between chronotype and intra-sexual competition. We tested the prediction that, in a subject population of young heterosexual men, evening-types would score higher on intra-sexual competition in the context of mating. The results were consistent with our prediction and showed that the association between chronotype and intra-sexual competitiveness is not the by-product of correlations with personality measures. Higher intra-sexual competitiveness in men who are evening-types may contribute to their higher short-term mating success reported by previous studies. Evolutionary hypotheses testing predictions derived from sexual selection or life history theory can make a significant contribution to our understanding of the functional significance of inter-individual variation in chronotype and its associated psychological and behavioral traits.

The slow and fast life histories of early birds and night owls: Their future- or present-orientation accounts for their sexually monogamous or promiscuous tendencies

Article

Oct 2014
EVOL HUM BEHAV

In this study we tested the hypothesis that inter-individual variation in morningness-eveningness (i.e., chronotype) is associated with variation in a composite measure of life history (the mini-K) such that morning-types (i.e., early birds) exhibit traits typically associated with slow life histories while evening-types (i.e., night owls) exhibit traits typically associated with fast life histories. In addition, we tested the hypothesis that time perspective may be one of the psychological mechanisms mediating the relationship between chronotype and socio-sexuality. Study participants were 95 heterosexual young men, most of whom were university students. Chronotype, life-history traits, socio-sexuality, and time perspective were assessed with well-established self-report measures. Variations in chronotype and in life-history traits were significantly associated in the direction predicted by our hypothesis. Consistent with our second hypothesis, time perspective emerged as a significant mediator of the association between chronotype and socio-sexuality so that the future orientation of morning-types was associated with their long-term mating orientation and relatively low sexual experience, while the present orientation of evening-types was associated with their short-term mating orientation and greater sexual experience. Our study provides the first evidence that variation in chronotype may be adaptive and elucidates one of the psychological mechanisms underlying the life history and reproductive strategies of male early birds and night owls.

What were “owls” doing in our ancestral photoperiodic environment? Chronobiological account for the evolutionary advantage of nocturnal lifestyle

Article

Full-text available

May 2014

Arcady Putilov

Since evolutionary process is slow, the human brain was adapted to the ancestral rather than today's environment. Therefore, genetic predisposition of young people to nocturnal lifestyle requires explanation. The pattern of age- and sex-associated differences revealed from self-reports of 2054 native and non-native residents of Turkmenia, Siberia, Yakutia, Chukotka and Alaska suggested that late bedtime preference might has evolved under sexual selection pressure. Moreover, simulation of experimental data on prolonged wakefulness indicated that differences between people preferring early, late and extremely late bedtimes (n = 39, 53 and 38, respectively) on wave-forms of their alertness rhythm can be explained by a relatively small circadian phase delay. It was hypothesized that, due to sexual division of daytime labour in ancestral societies, the late bedtime preference evolved to solve an adaptive problem of creation of early night lek for displaying throughout courtship various human-specific behaviours advertising high cognitive, music, gymnastic, artistic, language and humour abilities.

Morningness-eveningness and sociosexuality: Evening females are less restricted than morning ones

Article

Full-text available

May 2014
PERS INDIV DIFFER

Sociosexual orientation is a construct describing the propensity to engage in casual sex and sexual activity in uncommitted relationships, varying from restricted to unrestricted orientation. The personality profile of people exhibiting unrestricted sociosexuality matches a personality profile related to eveningness. Previous research on sociosexuality and morningness-eveningness is scarce, however, and conducted only with male participants. The present study aimed at testing whether eveningness is related to unrestricted sociosexuality in both genders. Participants were 352 (62.8% female) Poles aged between 17 and 57. They completed the reduced Morningness-Eveningness Questionnaire and the revised Sociosexual Orientation Inventory, consisting of three facets: behavior, attitude, and desire. The results revealed that females were more restricted than males in all facets of sociosexuality. Moreover, in both genders older age was related to less restricted behavior and attitude. Analyses showed that morningness-eveningness was unrelated to sociosexuality in males, but in females eveningness was linked to less restricted global sociosexuality (ρ = -0.272), and to less restricted sociosexual behavior (ρ = -0.182), attitude (ρ = -0.275) and desire (ρ = -0.151). Eveningness in females could be regarded as a contributory factor to the instability of romantic relationships and high-risk sexual behaviors.

Night Owl Women are Similar to Men in Their Relationship Orientation, Risk-taking Propensities, and Cortisol Levels: Implications for the Adaptive Significance and Evolution of Eveningness

Article

Full-text available

Jan 2014

Dario Maestripieri

Individual differences in morningness/eveningness are relatively stable over time and, in part, genetically based. The night-owl pattern is more prevalent in men than in women, particularly after puberty and before women reach menopause. It has been suggested that eveningness evolved relatively recently in human evolutionary history and that this trait may be advantageous to individuals pursuing short-term mating strategies. Consistent with this hypothesis, eveningness is associated with extraversion, novelty-seeking, and in males, with a higher number of sexual partners. In this study, I investigated whether eveningness is associated with short-term relationship orientation, higher risk-taking, and higher testosterone or cortisol. Both female and male night-owls were more likely to be single than in long-term relationships than early morning individuals. Eveningness was associated with higher risk-taking in women but not in men; this association was not testosterone-dependent but mediated by cortisol. Female night-owls had average cortisol profiles and risk-taking tendencies more similar to those of males than to those of early-morning females. Taken together, these findings provide some support to the hypothesis that eveningness is associated with psychological and behavioral traits that are instrumental in short-term mating strategies, with the evidence being stronger for women than for men.

An in-depth look into the association between morningness-eveningness and well-being: evidence for mediating and moderating effects of personality

Article

Full-text available

Oct 2018
CHRONOBIOL INT

Morningness-eveningness and standard personality traits are associated with well-being but few studies have directly compared the two types of construct as correlates of life satisfaction. Influences on well-being common to both chronotype and personality may include shared biological bases for depression and sleep disturbance, tendencies toward social jetlag, and emotion-regulation mechanisms. The current study tested mediation and moderation hypotheses in a sample of 379 Polish adults. The first hypothesis was that conscientiousness and emotional stability traits would mediate the relationship between morningness and life satisfaction. Consistent with previous results, morningness, the two personality traits, and satisfaction tended to be mutually positively correlated. A multiple mediation analysis showed that both traits partially mediated the morningness-satisfaction association. Data are compatible with morningness influencing personality development adaptively, although other causal hypotheses could be advanced. The second hypothesis was that extraversion would moderate the association between chronotype and satisfaction. This hypothesis was supported, with extraverted evening types showing disproportionately high life satisfaction, whereas introverted evening types showed the lowest levels of satisfaction. Level of extraversion may influence whether or not evening types choose to engage in adaptive social activities that boost well-being during the evening hours. Results demonstrate the importance of investigating both chronotype and personality in studies of well-being.

Article

Full-text available

Apr 2018

Recently, the issue of diurnal preferences has been increasingly studied within the context of romantic relationships and sexual functioning. In the present paper we apply a dyadic design to investigate the role of romantic partners' diurnal preferences in determining a variety of relationship outcomes. A sample of 91 heterosexual couples completed a set of questionnaires measuring relationship satisfaction, sexual satisfaction, and morningness-eveningness, and answered questions regarding their actual and preferred time for sexual activity. Conducted analyses revealed that similarity in chronotype between partners and female morningness fostered relationship satisfaction in females, but not in males. Furthermore, morningness-eveningness was associated with preferred time for sex in males, but not in females, who in principle preferred evening hours. Although actual time for sex was up to the female preference, sexual satisfaction in both genders was associated with lower discrepancy in their preferred time for sex and greater frequency of intercourse. In sum, these results indicate that chronotype and time for sex are important factors affecting sexual and relationships satisfaction in heterosexual couples.

Sleep timing is linked to sociosexuality: Evidence from German, Polish, Slovak and Spanish females

Article

Full-text available

Jan 2018
TIME SOC

Given the known relationship between eveningness and sociosexuality among females, the aims of this study were: (a) to analyze this relationship in four countries using midsleep time on free days and morning affect measures of morningness–eveningness and (b) to test the role of dark personality andother relevant control variables in this relationship. Data from 1483 females were collected from Poland, Spain, Germany, and Slovakia. Adjusting for age, relationship status, country, age at first intercourse, and Dark Triad traits, the most universal findings were that females with later sleep timing were less sociosexually restricted (3% shared variance with sociosexuality). Sleep timing played a greater role in sociosexuality compared to morning affect. This finding showed that Dark Triad personality is not involved in association between morningness–eveningness and sociosexuality and it added a value to the importance of sleep–wake habits in mating preferences.

Cortisol reactivity to psychosocial stress mediates the relationship between extraversion and unrestricted sociosexuality

Article

Nov 2015
PERS INDIV DIFFER

We investigated the hypotheses that extraversion is associated with unrestricted sociosexuality (operationalized as greater sexual experience and greater short-term mating orientation) and that this association is mediated by reduced cortisol reactivity to psychosocial stress. Study participants were heterosexual male college students (n = 109). Extraversion was assessed with the Big Five Inventory and sociosexuality was assessed with the Multidimensional Sociosexuality Orientation Inventory. Cortisol reactivity to psychosocial stress was assessed via three saliva samples collected immediately before, immediately after, and 15 min after the Trier Social Stress Test. Extraversion was associated with greater sexual experience but not with greater short-term mating orientation. As predicted, more extraverted individuals showed a lower increase in cortisol in response to psychosocial stress than less extraverted individuals. Previous sexual experience and short-term mating orientation were negatively correlated with cortisol reactivity to stress. Finally, mediation analyses confirmed our hypothesis that cortisol reactivity to psychosocial stress is a mechanism mediating the association between extraversion and unrestricted sociosexuality. These findings have implications for our understanding of the benefits and costs of different personality traits as well as for our understanding of the determinants or correlates of individual differences in sociosexuality.

Quo Vadis, Chronopsychology?

Article

Full-text available

Nov 2021

Arcady Putilov

This is the first review in chronopsychology, a relatively new interdisciplinary area of research which has developed rapidly at the junction of chronobiology, somnology, and psychology. Chronopsychology studies the mechanisms of rhythmicity in behavior and the mind based on methods of chronobiology, somnology, and psychometry. In particular, chronobiology studies biological clocks, while somnology addresses their influences on regulatory processes directly controlling the sleep–waking cycle, impairments to which have adverse impact on mental activity. Psychometric and differential psychology methods are widely used, for example, in studies of the chronotype and its relationship with a great diversity of human characteristics – genetic, psychophysiological, behavioral, cognitive, personality, and psychopathological. Particular attention is paid to sleep, drowsiness, fatigue, work/study productivity, and healthy/unhealthy lifestyles in people of different sexes and ages. Applied research includes the development – taking account of the chronotype of each specific person – of recommendations supporting preservation of good quality sleep and health in specific temporal situations, optimizing work/rest patterns, efficient assimilation of new skills, and preventing accidents during vigorous activity at times of day unsuitable for these activities.

The Human Sleep Paradox: The Unexpected Sleeping Habits of Homo sapiens

Article

Full-text available

Oct 2021
ANNU REV ANTHROPOL

David R Samson

The human sleep pattern is paradoxical. Sleep is vital for optimal physical and cognitive performance, yet humans sleep the least of all primates. In addition, consolidated and continuous monophasic sleep is evidently advantageous, yet emerging comparative data sets from small-scale societies show that the phasing of the human pattern of sleep–wake activity is highly variable and characterized by significant nighttime activity. To reconcile these phenomena, the social sleep hypothesis proposes that extant traits of human sleep emerged because of social and technological niche construction. Specifically, sleep sites function as a type of social shelter by way of an extended structure of social groups that increases fitness. Short, high-quality, and flexibly timed sleep likely originated as a response to predation risks while sleeping terrestrially. This practice may have been a necessary preadaptation for migration out of Africa and for survival in ecological niches that penetrate latitudes with the greatest seasonal variation in light and temperature on the planet. Expected final online publication date for the Annual Review of Anthropology, Volume 50 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Chronotype, social jetlag and sleep loss in relation to sex steroids

Article

May 2019

Chronotype describes preferences for functioning at different times of the day. At the onset of puberty, a sharp shift towards eveningness starts, reaching its peak at the end of adolescence, followed by a steady shift towards morningness as the ageing process occurs. Puberty is also the time when sex differences appear, with men being more inclined to eveningness than women, which diminishes around menopause; the described pattern of changes in chronotype leads to the hypothesis that reproductive hormones may be the driving factor behind this conversion. In the present study, we aimed to verify this hypothesis by analysing participants' testosterone, progesterone and dehydroepiandrosterone (DHEA) levels in the three months prior to the study, as indicated by assays in 3-cm hair strands from the scalp. Participants (n = 239) of both sexes also completed the Munich Chronotype Questionnaire. The results showed that in men higher testosterone levels were related to eveningness and less sleep loss, whereas greater sleep loss was associated with lower levels of DHEA. In women, no associations between chronotype and levels of the analysed hormones were found. The results support the hypothesis that testosterone levels play a role in shaping eveningness. We further hypothesised that a possible cause of the higher secretion level of testosterone in men with the evening chronotype is a mechanism to offset the negative consequences of sleep loss.

Der Chronotyp in Beziehungen und Sexualverhalten – eine erste Übersicht

Article

Aug 2018

Christoph Randler

Ein später Chronotyp (oder eine Eule) ist jemand, der seinen Zubettgehzeitpunkt eher auf späte Zeiten legt und deshalb auch später aufsteht. Im Gegensatz dazu stehen Morgentypen (Lerchen) früher auf und gehen früher zu Bett. Männer und Frauen unterscheiden sich im Chronotyp. So sind Frauen in der Regel etwas frühere Chronotypen. Dieser Unterschied entsteht interessanterweise mit dem Eintritt in die Pubertät und endet mit der Menopause, woraus sich eine reproduktive Funktion interpretieren lässt. Aus evolutiver darwinistischer Sichtweise handelt es sich hier um einen Sexualdimorphismus, der mit sexueller Selektion erklärt werden kann. Verschiedene Studien wiesen für Italien, Sri Lanka und Deutschland tatsächlich nach, dass Männer vom Abendtyp mehr Sexualpartnerinnen angaben. Darüber hinaus zeigen Studien, dass bei der Partnerwahl assortatives Verhalten erfolgt, d. h. dass sich eher Paare finden, deren Partner sich im Chronotyp ähnlich sind. Dennoch gibt es noch genügend unbeantwortete Fragestellungen in dieser Thematik.

Chronotype variation drives night-time sentinel-like behaviour in hunter–gatherers

Article

Full-text available

Jul 2017
Proc Biol Sci

Sleep is essential for survival, yet it also represents a time of extreme vulnerability to predation, hostile conspecifics and environmental dangers. To reduce the risks of sleeping, the sentinel hypothesis proposes that group-living animals share the task of vigilance during sleep, with some individuals sleeping while others are awake. To investigate sentinel-like behaviour in sleeping humans, we investigated activity patterns at night among Hadza hunter–gatherersof Tanzania. Using actigraphy, we discoveredthat all subjects were simultaneously scored as asleep for only 18 min in total over 20 days of observation, with a median of eight individuals awake throughout the nighttime period; thus, one or more individuals was awake (or in light stages of sleep) during 99.8% of sampled epochs between when the first person went to sleep and the last person awoke. We show that this asynchrony in activity levels is produced by chronotype variation, and that chronotype covaries with age. Thus, asynchronous periods of wakefulness provide an opportunity for vigilance when sleeping in groups. We propose that throughout human evolution, sleeping groups composed of mixed age classes provided a form of vigilance. Chronotype variation and human sleep architecture (including nocturnal awakenings) in modern populations may therefore represent a legacy of natural selection acting in the past to reduce the dangers of sleep. © 2017 The Author(s) Published by the Royal Society. All rights reserved.

How does chronotype mediate gender effect on Dark Triad?

Article

Apr 2017
PERS INDIV DIFFER

Research has shown an association between both eveningness and Dark Triad (DT) traits and some personality characteristics. In this study, we assessed the relationship between morningness-eveningness and DT personality traits. The sample consisted of 1393 students (mean age 22.95; 616 men and 777 women).We aimed for a gender balanced sample. Correlation, comparison, and mediation analyses were carried out. Findings showed negative correlations between Composite Scale of Morningness (CSM) scores and the DT composite, Machiavellianism and psychopathy. Age was neither correlated with DT traits, nor with CSM scores. Men scored higher than women on all three DT traits and women were more morning-oriented than men. Besides, findings indicated eveningness mediating gender's effect on all DT components slightly - except for narcissism. This study shed light on a previously unassessed aspect of chronotype as mediator in the relationship between gender and DT. Article link free access: http://www.sciencedirect.com/science/article/pii/S0191886916311813

Wise “birds” follow their clock: The role of emotional intelligence and morningness-eveningness in diurnal regulation of mood

Article

Full-text available

Jan 2016

Emotional intelligence (EI) and morningness-eveningness (M-E) preference have been shown to influence mood states. The present article investigates the way in which these two constructs may interact, influencing morning and evening mood levels. A sample of 172 participants completed a multidimensional mood scale measuring energetic arousal, tense arousal and hedonic tone at 7:00 and at 22:00. As expected, morning and evening types experienced higher energetic arousal at their preferred time of day; effects of M-E on other mood dimensions were weaker. EI was found to correlate with lower tense arousal, but the association was stronger in the evening, perhaps reflecting the value of EI in managing the social events characteristic for the evening hours. An interactive effect of EI and M-E was found for both diurnal changes and morning levels of energetic arousal. Namely, in individuals higher in EI there appeared a more marked synchrony effect between chronotype and mood, which was absent in those low in EI; individuals higher in EI showed more pronounced diurnal changes in energetic arousal characteristic for their chronotype (i.e., higher energetic arousal at morning hours in morning chronotypes; higher energetic arousal at evening hours in evening chronotypes), while in participants low in EI, diurnal changes in energetic arousal were smaller. Moreover, the characteristic positive association between morningness and energetic arousal during morning hours was apparent only in those high in EI. These findings suggest that individual differences in circadian variation in mood reflect several factors, including an endogenous rhythm in energy, the distribution of social activities throughout the day, and the person’s awareness of their own energy level.

Sleep duration and chronotype in adults in Côte d’Ivoire: Influence of gender, religion and age

Article

Full-text available

Aug 2015

This study investigated the sleep-wake rhythm and chronotype of people living in Côte d’Ivoire. We assessed sleep-wake behaviour in 556 adults (336 men, 220 women) between 25 and 54 years (mean: 38.63) by means of structured interviews. Data were analysed by linear models with sleep wake variables as dependent variables and age, gender, religion and region (urban/rural) as fixed factors controlling for number of working hours and children. Results suggest sleep length not to differ between weekdays and weekends but sleep timing (chronotype) was later on weekends with a midpoint of sleep at 1:37am during weekdays compared to 1:58am on weekends. The more children, the earlier was the midpoint of sleep and the shorter was sleep length. Midpoint of sleep was earlier in older people. Women slept longer during weekdays and were earlier chronotypes. Sleep duration was longer in the rural areas and midpoint of sleep was later in the urban areas on weekdays and on the weekend. Muslims showed the shortest sleep duration and were earliest chronotypes. Sleep-wake cycles in the African setting sample were shorter for women, Moslems, and older people.

Relationship between sleep time preference of adolescents and their parents

Article

Nov 2014

This study aimed to explore the relationship between sleep time preference of adolescents and their parents, considering gender separately. To this end, 912 adolescents (501 females) from 10 to 17 years were administered the Morningness–Eveningness Questionnaire for Children and Adolescents and their parents filled in the Morningness–Eveningness Questionnaire. To assess sleep time preference, the ideal midpoint of sleep was computed. A mathematical function was developed in order to correct the evolution of the ideal midpoint of sleep over time. The actual values were adjusted on the basis of those provided by the function for a specific age and gender and then reclassified into a new ordinal variable, with five categories, according to the interval where difference between actual and predicted values lies. This variable is informative as to the degree and magnitude of the ideal midpoint of sleep dispersion regarding/compared to the average value for a certain age and sex, represented by estimated function. The correlations between actual values of the ideal midpoint of sleep of adolescents and actual values of their parents, separately for gender of both, were not significant. The “corrected” ideal midpoint of sleep of daughters resulted significantly correlated with those “corrected” of mothers and fathers; furthermore, these correlation values were significantly higher than those detected between daughters and unrelated parents, highlighting the fact that such a privileged relationship between daughters and both parents is not due to chance.

Predicting school achievement: The role of inductive reasoning, sleep length and morningness–eveningness

Article

Full-text available

Mar 2013
PERS INDIV DIFFER

Adolescents move to evening orientation just when school schedule becomes earlier. Whereas school achievement has been associated to morningness orientation during morning school schedule, some studies have indicated that evening people are more intelligent. In this study the relative contribution of Morningness–Eveningness (M–E) in the prediction of school achievement, after controlling for age, sex/gender, inductive reasoning and sleep length was analyzed. Participants were 887 adolescents (aged 12–16). School achievement was evaluated using Grade Point Average (GPA), inductive reasoning was evaluated by reasoning subtest of Primary Mental Abilities (PMA-R), sleep length was calculated from rise time and bedtime questions, and M–E was evaluated by Morningness–Eveningness Scale for Children (MESC). Evening adolescents scored higher on PMA-R and obtained lower GPA. Inductive reasoning, age, sex/gender, sleep length and M–E accounted for 19% variance percentage on GPA. M–E was a significant predictor of school achievement even after controlling for traditional predictors, albeit slightly.

Chronotyp und soziales Verhalten

Chapter

Mar 2024

Christoph Randler

Morningness, Eveningness, and Life Satisfaction

Chapter

Feb 2024

Christoph Randler

Взаимосвязь свойств Темной триады и хронотипических предпочтений

Article

Oct 2015

Приводятся результаты исследования взаимосвязей хронотипических особенностей суточной активности и личностных свойств Темной триады. Основываясь на предыдущих работах, можно предполагать, что макиавеллизм, нарциссизм и психопатия связаны с предпочтениями вечернего хронотипа. Выборку составили 191 студент пермских вузов, возраст 18–25 лет. Для проверки гипотез использовались краткая форма опросника «Темная триада» и краткая версия «Утренне-вечернего опросника» (Morningness-Eveningness Questionnaire). Полученные данные обрабатывались корреляционным и множественным регрессионным анализом. В результате было обнаружено, что макиавеллизм связан со склонностью к утреннему, а психопатия – к вечернему хронотипу. Нарциссизм не обнаруживает связей с хронотипическими особенностями.

Камо грядеше, хронопсихология?

Article

Full-text available

Jan 2021
ZH VYSSH NERV DEYAT+

Arcady Putilov

QUŌ VĀDIS, CHRONOPSYCHOLOGY? A. A. Putilov This is the first review on chronopsychology, a relatively new interdisciplinary research field that is rapidly developing at the crossroads of chronobiology, sleep science, and psychology. By applying the methods of chronobiology, sleep science, and psychometry, it explores the mechanisms of rhythmicity of behavior and psychic activity. In particular, chronobiology studies the biological clocks, and sleep science explores their influence on the regulatory processes governing the sleep- wake cycle which disturbance negatively affects mental and physical activity. Chronopsychology al- so relies on the methods developed by personality psychologists in the framework of psychometrics, for example, in the study of chronotype and its relationship with a variety of other human charac- teristics – genetics, psychophysiological, behavioral, cognitive, personality and psychopathologi- cal. Special attention is devoted to sleep, sleepiness, fatigue, productivity of work/study, healthy/unhealthy lifestyles of people of different sex and age. Applied research includes the devel- opment – with taking into account the chronotype of a particular person – recommendations for getting adequate sleep and maintaining good health in a specific temporal environment, optimizing work and rest schedules, effective learning new skills, preventing accidents associated with activity at inappropriate time of the day. Это первый обзор по хронопсихологии, относительно новой междисциплинарной области исследований, которая быстро развивается на стыке хронобиологии, сомнологии и психо-логии. Хронопсихология изучает механизмы ритмичности в поведении и психике, опира-ясь на методы хронобиологии, сомнологии и психометрии. В частности, хронобиология изучает биологические часы, а сомнология-их влияние на регуляторные процессы, непо-средственно контролирующие цикл сна и бодрствования, нарушения которого отрица-тельно влияют на психическую деятельность. Mетоды психометрии и дифференциальной психологии широко применяются, например, при изучении хронотипа и его взаимосвязи с самыми разными особенностями человека-генетическими, психофизиологическими, поведенческими, когнитивными, личностными и психопатологическими. Особое внима-ние уделяется сну, сонливости, усталости, продуктивности работы/учебы, здоровому/не-здоровому образу жизни людей разного пола и возраста. Прикладные исследования вклю-чают разработку-с учетом хронотипа каждого конкретного человека-рекомендаций по сохранению полноценного сна и здоровья в конкретной временной среде, оптимизации режима работы и отдыха, эффективному усвоению новых навыков и предотвращению не-счастных случаев при активной деятельности в неподходящее для такой деятельности вре-мя суток. Ключевые слова: хронотипология, сомнология, хронобиология, психология личности, ин-дивидуальные различия, циркадианные ритмы, регуляция сна-бодрствования, сонли-вость, сменный труд ВВЕДЕНИЕ Слово "chronopsychology" ("хронопсихо-логия") не сложно обнаружить на просторах интернета. Оно на слуху уже не одно десяти-летие, а с 1999 г. японская hip hop группа M-Flo исполняет небезызвестную песню с таким названием. Парадокс, однако, состоит в том, что намного сложнее ответить на вопрос о том, что же из себя представляет область на-учных исследований, обозначенная словом "хронопсихология". Причем ответ не дает не только прослушивание этой песни, но и бо-лее серьезное изучение всех научных источ-ников, содержащих данное слово. Среди них, в частности, нельзя обнаружить обзор по ис-тории и современному состоянию хронопси-хологии как на английском, так и на русском языке. Так что данный обзор, похоже, станет первым. Будучи относительно молодой областью междисциплинарных исследований, хроно-психология стремительно развивается в по-следние годы на стыке хронобиологии, сомно-логии и психологии. Она изучает механизмы и проявления ритмичности в поведенческих и психологических процессах. Ее теоретиче-скими фундаментами являются две биологи-ческие дисциплины-хронобиология и со-мнология. В сферу экспериментальных ис-следований первой входят биологические часы, а в сферу интересов второй-их влия-ние на те регуляторные процессы, которые непосредственно контролируют цикл сна и бодрствования. Серьезные нарушения этого цикла-а с этим знаком практически каждый человек-отрицательно влияют на психиче-УДК 57.034+159.91 ОБЗОРЫ И ТЕОРЕТИЧЕСКИЕ СТАТЬИ

Chronotype and Social Behavior

Chapter

Dec 2019

Christoph Randler

A late chronotype (or an owl) is someone who tends to go to bed late, so he or she will get up later. In contrast, morning types (larks) get up earlier and go to bed earlier. Men and women differ in their chronotype. Women are usually earlier chronotypes, who go to bed earlier and fall asleep earlier, and then get up a little earlier. Interestingly, this difference arises with puberty and ends with menopause, from which a reproductive function is suggested. From an evolutionary Darwinian perspective, this is a sexual dimorphism that can be explained by sexual selection. Various studies have indeed shown that men of the evening type reported more sexual partners, in Italy, Sri Lanka and Germany. Furthermore, studies show that assortative mating takes place when choosing a partner, i.e. couples have more similar chronotypes. However, there are still many open questions related to this topic. Other evidence from this brief overview showed that morning people are more extraverted and agreeable. One of the unresolved questions is are these relationships and associations a result of shorter sleep and restricted sleep or is this a basic biological link. If the former is the case, extending sleep duration for owls, especially during the week, would increase quality of life and may have a positive impact on social behavior.

Взаимосвязь свойств Темной триады и хронотипических предпочтений / The Dark triad and chronotype

Article

Full-text available

Oct 2015

The article presents the research results of the relationship between the chronotype of daily activities and the personality traits of Dark triad. Basing on P.Johnason’s studies we proposed that Machiavellianism, narcissism and psychopathy are associated with the preferences in the evening-oriented chronotype. The sample consists of 191 undergraduate students, age 18-25 years. The short form of Dark triad questionnaire and the short version of the Morningness-Eveningness Questionnaire are used. The data were processed by the correlation (Pearson) and multivariate regression analysis. As a result, it was found that machiavellianism is associated with preference in morning-oriented chronotype and psychopathy - in evening-oriented chronotype. Narcissism does not show association with chronotype. Приводятся результаты исследования взаимосвязей хронотипических особенностей суточной активности и личностных свойств Темной триады. Основываясь на предыдущих работах, можно предполагать, что макиавеллизм, нарциссизм и психопатия связаны с предпочтениями вечернего хронотипа. Выборку составили 191 студент пермских вузов, возраст 18–25 лет. Для проверки гипотез использовались краткая форма опросника «Темная триада» и краткая версия «Утренне-вечернего опросника» (Morningness-Eveningness Questionnaire). Полученные данные обрабатывались корреляционным и множественным регрессионным анализом. В результате было обнаружено, что макиавеллизм связан со склонностью к утреннему, а психопатия – к вечернему хронотипу. Нарциссизм не обнаруживает связей с хронотипическими особенностями.

Personality and chronotype - A concept for bird research?

Article

May 2014

Christoph Randler

This article deals with the concepts of sleep, sleep timing and personality in birds. Previous psychological studies in humans addressed these questions and they became a flourishing research field combining many aspects of psychology, physiology and medicine. Here, I discuss whether these aspects can be transferred to the field of ornithology because psychological studies increasingly are transferred to the field of animal behaviour and ornithology (e.g., the concept of personality). The article gives an overview over the studies dealing with birds and how they are related to studies in psychology.

Eveningness is Associated with Higher Risk-Taking, Independent of Sex and Personality

Article

Dec 2014

-This study tested the hypotheses that eveningness is associated with higher risk-taking propensities across different domains of risk and that this association is not the result of sex differences or confounding covariation with particular personality traits. Study participants were 172 men and women between 20 and 40 years of age. Surveys assessed chronotype, domain-specific risk-taking and risk-perception, and Big Five personality dimensions. Eveningness was associated with greater general risk-taking in the specific domains of financial, ethical, and recreational decision making. Although risk-taking was associated with both risk perception and some personality dimensions, eveningness predicted risk-taking independent of these factors. Higher risk-taking propensities among evening types may be causally or functionally linked to their propensities for sensation- and novelty-seeking, impulsivity, and sexual promiscuity.

Sleep, sleep timing and chronotype in animal behaviour

Article

Aug 2014
ANIM BEHAV

Christoph Randler

In humans, sleep duration and sleep timing have been identified as interesting facets of individual differences and of personality. Sleep duration and sleep timing are different constructs. For example, compare two individuals both sleeping for 6 h: one may sleep from 2300 to 0500 hours and the other from 0100 to 0700 hours. One can assess the midpoint of sleep in these two subjects which is the midpoint in clock time between sleep onset and awakening. These ideas have already been picked up in a handful of studies. Sex differences have been found in birds in the same direction as in humans with males sleeping for less time. Contrasting effects have been found in relation to mating: in humans, late chronotype men have the highest mating success, whereas in birds, earlier chronotypes gain higher mating success. Many sleep parameters are related to assortative mating in humans and similar but weaker relationships have been found in birds. Ontogenetic studies show that sleepewake behaviour changes during adolescence in humans. Such changes have also been found in other mammals ranging from primates to rodents. Factors determining sleepewake patterns could be environmental, such as temperature, sunrise or sunset or even artificial light at night. Artificial lighting at night leads to an earlier wake up and singing time in blackbirds, Turdus merula, whereas light at night makes humans wake up later. As a conclusion, I show some parallels and differences in the study of sleep timing between animals and humans and encourage further studies, in both field and laboratory settings.

Aggression in Young Adults — A Matter of Short Sleep and Social Jetlag?

Article

Dec 2013

Evening orientation and sleep duration have been linked with aggression and problematic behaviors, but no study has used an explicit aggression questionnaire. The present study used the Buss-Perry Aggression Questionnaire based on physical aggression, verbal aggression, anger, and hostility, as well as questionnaires on the timing of sleep and sleep duration to assess this relationship in young adult men. The Composite Scale of Morningness was used to assess circadian preference; sleep-wake variables (wake time and sleep onset time on weekdays and on weekend days) were used to calculate midpoint of sleep, social jetlag, and sleep duration. Results indicated that sleep duration correlated negatively with verbal aggression, physical aggression, and anger. Short sleepers were more aggressive. Using multivariate analysis of variance, shorter sleep duration was a significant predictor of verbal aggression and anger. Concerning physical aggression, social jetlag also contributed to the model. Morningness-eveningness was associated with the hostility scale with eveningness related to higher hostility. Men scored higher than women in physical and verbal aggression.

Women would like their Partners to be more Synchronized with them in their Sleep-Wake Rhythm

Article

Full-text available

Oct 2014

Men sleep shorter and go to bed and get up later than women, thus they are later chronotypes. This difference between the sexes is most pronounced between puberty and menopause indicating the possibility that morningness is subject to sexual dimorphism related to reproductive aspects. The objective of the study was to compare the sleep-wake behavior of women with their actual partners and with their preferred partners. As a hypothesis, we expect some assortment in mating concerning chronotype (with the actual partner), but we also expect a higher synchronization with a preferred ideal partner. 167 women were analysed in this study (mean age: 23.0 ± 2.57 (SD) years). Mated women were earlier chronotypes than their partners (t = –2.051, p = .042, d = .34) but the difference was small (11:02 min ± 1:04 min). The results of the present study showed women preferring a partner synchronized to their own sleep-wake-rhythm more than their actual partners were. The above result was true either for single facets of the sleep-wake rhythm (e.g. bed time, sleep onset) or for midpoint of sleep on free days – an indicator of actual chronotype: women’s and their partners’ correlation of midpoint of sleep was lower (r = .513) than women’s and their ideal partners’ correlation (r = .855). Amongst various sleep-wake measures, women particularly preferred a partner going to bed at the same time. Assortative mating according to sleep-wake rhythm exists, but women for long-term pair-bonds would like their partners far more synchronized.

Evidence of Sexual Selection for Evening Orientation in Human Males: A Cross Cultural Study in Italy and Sri Lanka

Article

Full-text available

Oct 2011

Previous research has established the existence of individual differences with regards to individuals' optimum time of well-functioning; specifically in terms of being either morning or evening oriented. An association has also emerged between being more evening, as opposed to morning, oriented and having a greater number of sexual partners. The aim of the present study was to investigate whether "eveningness" in males is an evolved sexually dimorphic trait consistent across different cultures. A sample of 179 male Sri Lankan men residing in two different cultural and economic settings, Italy and Sri Lanka, were administered the Morningness-Eveningness Questionnaire (MEQ) followed by assessing their sexual behavior history. The results robustly portrayed a highly significant main effect of MEQ types highlighting the twofold sexual success enjoyed by the evening individuals in both regional locations. Morning oriented individuals, showed a stronger preference for going out and partying than evening-types, suggesting that the higher mating success of evening types is not due to their different lifestyles allowing more opportunities to encounter females. However, evening types exhibited a preference for flirtatious behaviors in the later part of the day. Shoulder-to-hip and handgrip strength, as measures of testosterone levels, were not significantly associated with eveningness. The results are discussed in terms of sexual selection and its interplay with human cultural variation.

Beauty and the beast: Mechanisms of sexual selection in humans

Article

Full-text available

May 2010
EVOL HUM BEHAV

David A Puts

Literature in evolutionary psychology suggests that mate choice has been the primary mechanism of sexual selection in humans, but this conclusion conforms neither to theoretical predictions nor available evidence. Contests override other mechanisms of sexual selection; that is, when individuals can exclude their competitors by force or threat of force, mate choice, sperm competition, and other mechanisms are impossible. Mates are easier to monopolize in two dimensional mating environments, such as land, than in three-dimensional environments, such as air, water, and trees. Thus, two-dimensional mating environments may tend to favor the evolution of contests. The two-dimensionality of the human mating environment, along with phylogeny, the spatial and temporal clustering of mates and competitors, and anatomical considerations, predict that contest competition should have been the primary mechanism of sexual selection in men. A functional analysis supports this prediction. Men's traits are better designed for contest competition than for other sexual selection mechanisms; size, muscularity, strength, aggression, and the manufacture and use of weapons probably helped ancestral males win contests directly, and deep voices and facial hair signal dominance more effectively than they increase attractiveness. However, male monopolization of females was imperfect, and female mate choice, sperm competition, and sexual coercion also likely shaped men's traits. In contrast, male mate choice was probably central in women's mating competition because ancestral females could not constrain the choices of larger and more aggressive males through force, and attractive women could obtain greater male investment. Neotenous female features and body fat deposition on the breasts and hips appear to have been shaped by male mate choice.

Morning and evening-types: Exploring their personality styles

Article

Full-text available

Sep 2007
PERS INDIV DIFFER

Juan F. Díaz-Morales

The aim of the present study was to explore the personality styles of morning and evening-types. Given that personality aspects of both types are a consequence of their coping with environmental and social demands, it was reasonable to consider the extent to which morning and evening-types differ, both in the way they perceive the environment and negotiate with others in their social spheres. A sample of 360 university students, age range 18–30 years completed the Composite Scale of Morningness (CSM), and Millon Index of Personality Styles (MIPS). As well as sex differences on personality styles, the results showed that morningness–eveningness orientation was related both to the manner in which individuals seek out, regulate, internalize, and transform information about their environments and themselves (thinking styles), and to the way in which people relate to and negotiate with others in their social spheres (behaving styles), mediating the feelings that motivate them and cognitions they have come to have.

The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature

Book

Full-text available

Jan 2001

Geoffrey Miller

The mating mind' revives and extends Darwin's suggestion that sexual selection through mate choice was important in human mental evolution - especially the more 'self-expressive' aspects of human behavior, such as art, morality, language, and creativity. Their 'survival value' has proven elusive, but their adaptive design features suggest they evolved through mutual mate choice, in both sexes, to advertise intelligence, creativity, moral character, and heritable fitness. The supporting evidence includes human mate preferences, courtship behavior, behavior genetics, psychometrics, and life history patterns. The theory makes many testable predictions, and sheds new light on human cognition, motivation, communication, sexuality, and culture.

Age and Gender Differences in Morningness–Eveningness During Adolescence

Article

Full-text available

Jul 2011

Christoph Randler

Morningness-eveningness was assessed in a large sample of adolescents and young adults. Morningness decreased from 12 to 15 years, and then remained on a stable level until about 20 years, when a turn back to morningness occurred. Boys and men were on average more evening-oriented than were girls and women. In detail, significant differences existed at the ages of 16, 18, and 19 years. A quadratic function explained more variance than a linear regression. Composite Scale of Morningness scores are related to puberty scores in boys and girls, and when combining data (i.e., higher pubertal development was related to eveningness).

Season of Birth and Morningness: Comparison Between the Northern and Southern Hemispheres

Article

Full-text available

Jul 2011
CHRONOBIOL INT

The present study explored the possible role of the photoperiod at birth on morningness by collecting data in the northern (Italy) and southern (Australia) hemispheres. To assess circadian typology, the Composite Scale of Morningness (CS) was administered to a sample of 1734 university students (977 Italian and 757 Australian; 1099 females and 635 males; age 24.79 ± 7.45 yrs [mean ± SD]). Consistent with the literature, females reported higher CS scores (morningness) than males, and Australian participants reported higher CS scores than Italian participants. Allowing for the fact the seasons are reversed between the hemispheres, the results are in line with previous studies. The authors found more evening types were born during the seasons associated with longer photoperiod (spring and summer), and more morning types were born during the seasons associated with shorter photoperiod (autumn and winter), indirectly supporting an imprinting-like phenomenon played by the photoperiod at birth.

Sex difference in the near-24-hour intrinsic period of the human circadian timing system

Article

Full-text available

May 2011
P NATL ACAD SCI USA

The circadian rhythms of melatonin and body temperature are set to an earlier hour in women than in men, even when the women and men maintain nearly identical and consistent bedtimes and wake times. Moreover, women tend to wake up earlier than men and exhibit a greater preference for morning activities than men. Although the neurobiological mechanism underlying this sex difference in circadian alignment is unknown, multiple studies in nonhuman animals have demonstrated a sex difference in circadian period that could account for such a difference in circadian alignment between women and men. Whether a sex difference in intrinsic circadian period in humans underlies the difference in circadian alignment between men and women is unknown. We analyzed precise estimates of intrinsic circadian period collected from 157 individuals (52 women, 105 men; aged 18-74 y) studied in a month-long inpatient protocol designed to minimize confounding influences on circadian period estimation. Overall, the average intrinsic period of the melatonin and temperature rhythms in this population was very close to 24 h [24.15 ± 0.2 h (24 h 9 min ± 12 min)]. We further found that the intrinsic circadian period was significantly shorter in women [24.09 ± 0.2 h (24 h 5 min ± 12 min)] than in men [24.19 ± 0.2 h (24 h 11 min ± 12 min); P < 0.01] and that a significantly greater proportion of women have intrinsic circadian periods shorter than 24.0 h (35% vs. 14%; P < 0.01). The shorter average intrinsic circadian period observed in women may have implications for understanding sex differences in habitual sleep duration and insomnia prevalence.

Normative Data on the Sleep Habits of Australian Children and Adolescents

Article

Full-text available

Oct 2010

To provide normative sleep data on 9-18 year old Australians. Cohort study. Participants' homes. 4032 Australians aged 9-18 years. N/A. Participants completed a 48h use of time recall, comprising sleep data for one complete night. Sleep duration, bedtime and wake time were compared across age groups, between genders, and between school and non-school days using ANOVA. Sleep duration declined with age (P < 0.0001) at the rate of 12 min/night per year of age on school days, and 4 min on non-school days. Girls slept slightly longer than boys (5 min/night; P = 0.03). Non-school day sleep was 16 min longer than school day sleep (P < 0.0001), with the difference increasing with age. Bedtimes got later with age (P < 0.0001), however there were no differences in bedtimes between boys and girls. Bedtimes occurred 34 min later on non-school days (P < 0.0001). Wake times were very similar across age groups on school days, but increased at the rate of 10 min/year of age on non-school days. Wake times were similar for boys and girls, and occurred on average 82 min later on non-school days (P < 0.0001). Overall, 17% of school days and 20% of non-school days failed to meet the American Centers for Disease Control and Prevention sleep duration guidelines. Normative sleep data will provide a valuable yardstick for health and education professionals when dealing with sleep-related issues.

Assessment of Chronotype in Four- to Eleven-Year-Old Children: Reliability and Validity of the Children's ChronoType Questionnaire (CCTQ)

Article

Full-text available

Aug 2009
CHRONOBIOL INT

Individual differences in circadian phase preference ("chronotype") are linked to sleep schedule variability, psychosocial functioning, and specific properties of the circadian clock. While much is known about the development, distribution, and variability of chronotype in adolescents and adults, assessment in prepubertal children has been hindered by a lack of appropriate, reliable, and valid measures. This study presents a detailed description of the assessment of children's chronotype by the Children's ChronoType Questionnaire (CCTQ). The CCTQ is a parent-report, 27-item mixed-format questionnaire resulting in multiple measures of chronotype in 4- to 11-yr-old children: the midsleep point on free days (MSF), a morningness/eveningness scale (M/E) score, and a five-point chronotype (CT) score. The study provides validity data using actigraphy as well as test-retest reliability data for all three chronotype measures and sleep/wake parameters. Overall, the findings indicate moderate to strong agreement between the three measures, adequate associations between chronotype measures and sleep/wake parameters assessed by actigraphy, and excellent temporal stability (reliability).

Consequences of the Timing of Menarche on Female Adolescent Sleep Phase Preference

Article

Full-text available

Feb 2009
PLOS ONE

Most parents experience their children's puberty as a dramatic change in family life. This is not surprising considering the dynamics of physical and psychosocial maturation which occur during adolescence. A reasonable question, particularly from the parents' perspective, is: when does this vibrant episode end and adulthood finally start? The aim of the present study was to assess the relationship between puberty and the changes in sleep phase preferences during female maturation and adulthood by a cross-sectional survey. The results from 1'187 females aged 5 to 51 years based on self-report measures of sleep preferences on weekdays and on free days as well as the occurrence of menarche, show that in contrast to prepubertal children, adolescent females exhibit a striking progression in delaying their sleep phase preference until 5 years after menarche. Thereafter, the sleep phase preference switches to advancing. The current study provides evidence that a clear shift in sleep-wake cycles temporally linked to menarche heralds the beginning of "adult-like" sleep-wake behaviour in women and can be used as a (chrono)biological marker for the onset of adulthood.

Season of Birth, Gender, and Social-Cultural Effects on Sleep Timing Preferences in Humans

Article

Full-text available

Apr 2009

The present study aimed to analyze season of birth effects on preferred sleep-wake cycle timing as assessed by Morningness-Eveningness Questionnaire (MEQ). The MEQ was administered to a sample of 5,720 university students (3,851 Italians and 1,869 Spaniards; 3,877 female and 1,843 male; mean age 22.23 +/- 2.98 years). Females preferred to go to bed significantly earlier and sleep longer than males, regardless of season of birth and nationality. Subjects born in spring and summer went to bed and reached midpoint of sleep later than subjects born in fall and winter. Nationality significantly affected all the sleep parameters considered except duration. Overall, the effect of the season of birth on sleep preference timing was significant but quantitatively small. We suggest an evolutionary context for the different contributions of genetic and environmental factors in modulating sleep-wake cycles in humans.

The Effect of Diurnal Variation on Clinical Measurement of Serum Testosterone and Other Sex Hormone Levels in Men

Article

Full-text available

Dec 2008
J CLIN ENDOCR METAB

Although diurnal variation of testosterone and other hormones in men has been well documented, the effect of this variation on sampling during typical clinic hours has not been examined. Our objective was to examine temporal variation in serum testosterone and five other hormones in men over normal clinic hours. Blood samples were collected at six separate visits, three morning visits 1-3 d apart and three afternoon visits 1-3 d apart. In Boston, MA, 66 men participated, 30-80 yr of age, randomly selected from the Boston Area Community Health Survey who completed at least five visits. The age-specific ratio of hormone level at times ranging from 0801-1600 h to hormone level at 0800 h was calculated. Ratios were calculated from parameter estimates obtained from cosinor models. In men 30-40 yr old, testosterone levels were 20-25% lower at 1600 h than at 0800 h. The difference declined with age, with a 10% difference at 70 yr. 17 men with at least one of three measurements less than 300 ng/dl (10.4 nmol/liter) after 1200 h had normal testosterone levels at all three visits before 1200 h (five of eight men 30-47 yr old, four of nine men 66-80 yr old). Much lower levels of diurnal variation were found for dihydrotestosterone, SHBG, LH, FSH, and estradiol at all ages. Our results support the recommendation of restricting testosterone measurements to morning hours in both young and older men. Limited diurnal variation in other hormones indicates that sampling through the day is appropriate.

Individual Differences in the Amount and Timing of Salivary Melatonin Secretion

Article

Full-text available

Feb 2008
PLOS ONE

Background The aim of this study was to examine individual differences in a large sample of complete melatonin profiles not suppressed by light and search for possible associations between the amount and timing of melatonin secretion and a multitude of lifestyle variables. The melatonin profiles were derived from saliva samples collected every 30 minutes in dim light from 85 healthy women and 85 healthy men aged 18–45 years. There was a large individual variability in the amount of melatonin secreted with peak values ranging from 2 to 84 pg/ml. The onset of melatonin secretion ranged from 18:13 to 00:26 hours. The use of hormonal birth control, reduced levels of employment, a smaller number of days on a fixed sleep schedule, increased day length and lower weight were associated with an increased amplitude of melatonin secretion. The use of hormonal birth control, contact lenses, a younger age, and lower ratings of mania and paranoia were associated with a longer duration of melatonin secretion. An earlier occurrence of the onset of melatonin secretion was associated with an earlier wake time, more morningness and the absence of a bed partner. Lifestyle and behavioral variables were only able to explain about 15% of the individual variability in the amount of melatonin secretion, which is likely because of a substantial genetic influence on the levels of melatonin secretion.

Mate Selection-A Selection for a Handicap

Article

Full-text available

Oct 1975

Amotz Zahavi

It is suggested that characters which develop through mate preference confer handicaps on the selected individuals in their survival. These handicaps are of use to the selecting sex since they test the quality of the mate. The size of characters selected in this way serve as marks of quality. The understanding that a handicap, which tests for quality, can evolve as a consequence of its advantage to the individual, may provide an explanation for many puzzling evolutionary problems. Such an interpretation may provide an alternative to other hypotheses which assumed complicated selective mechanisms, such as group selection or kin selection, which do not act directly on the individual.

Gender differences in Morningness-eveningness preference

Article

Full-text available

Jul 2002

Morningness-eveningness preference (morning-, intermediate-, evening-type) or circadian typology is the individual difference that most clearly explains the variations in the rhythmic expression of biological or behavioral patterns. The aim of this study was to analyze gender difference in morningness-eveningness preference using the Horne and Ostberg questionnaire in the largest university student population selected so far (N = 2135), with an age range 18-30 yr. Morningness-eveningness questionnaire (MEQ) score distribution closely correlated to the normal curve (range 17-78, mean = 48.25; SD = 10.11), with 338 (15.84%) morning-types, 1273 (59.62%) intermediate-types, and 524 (24.54%) evening-types. The men and women differed significantly in their mean scores (p < 0.0001) and distribution per circadian typology (p < 0.00001), with the men presenting a more pronounced eveningness preference. Three factors were identified by factor analysis: time of greatest efficiency (I), sleep time/sleep phase (II), awakening time/sleep inertia (III). The MEQ items sensitive to gender differences were essentially those included in factor I and factor II. The results are discussed in relation to recent models of circadian regulation of the sleep-wake cycle.

Modifying Effects of Perceived Adaptation to Shift Work on Health, Wellbeing, and Alertness on the Job among Nuclear Power Plant Operators

Article

Full-text available

Feb 2005

This study examined the relationship between perceived adaptation to shift work and shift-related problems. A total of 608 male operators at nuclear power plants completed a set of validated questionnaires including a modified version of the Standard Shiftwork Index, which covered adaptation to shift work, fit to job content, chronotypes, chronic fatigue, sleep, naps, shift work locus of control (SHLOC), psychological health, social/family life, daytime sleepiness, workload, alertness on the job, and lifestyle factors. Participants were divided into two groups according to their perceived level of adaptation to shift work. The good adaptation group showed better outcomes than the poor adaptation group in terms of fit to job content, chronic fatigue, daytime sleep before night shifts, social and family disruption, SHLOC, psychological health, and alertness during night shifts (ps<0.001). Operators who reported good adaptation also took a more frequent, longer nap and more cigarettes during night shifts (ps<0.05). The cross-sectional study design cannot determine a causal relationship between perceived adaptation and shift work problems, yet the present results suggest that the effects of working shifts may be modified by perceptions of shift work adaptation.

Time for sex: nycthemeral distribution of human sexual behavior

Article

Full-text available

Apr 2005

Roberto Refinetti

Background Nycthemeral (daily) oscillation has been documented in a variety of physiological and behavioral processes. The present study was carried out to evaluate the existence of a nycthemeral rhythm of human sexual behavior and to identify environmental factors responsible for the rhythmic pattern. Methods Non-traditional university students (ages 18 to 51 years) recorded the times of day when they went to sleep, when they woke up, and when they had sex for 3 consecutive weeks. They also answered a questionnaire designed to identify the causes of their selection of time for sex. Results The majority of sexual encounters took place at bedtime (11 pm to 1 am). The most common explanations for this temporal pattern were the rigidity of the professional work schedule and family obligations and the availability of the partner, which reduced the opportunity for sexual encounters at other times of the day. Conclusion Most sexual encounters take place around bedtime. Although the presence of an endogenous component responsible for this temporal pattern cannot be excluded, the evidence indicates strong environmental forcing, particularly from the work/family schedule of the individuals and from partner availability.

Normative Data on the Sleep Habits of Australian Children and Adolescents

Article

Oct 2010

Study Objective To provide normative sleep data on 9-18 year old Australians. Design Cohort study. Setting Participants' homes. Participants 4032 Australians aged 9-18 years. Interventions N/A Measurements and Results Participants completed a 48h use of time recall, comprising sleep data for one complete night. Sleep duration, bedtime and wake time were compared across age groups, between genders, and between school and non-school days using ANOVA. Sleep duration declined with age (P < 0.0001) at the rate of 12 min/ night per year of age on school days, and 4 min on non-school days. Girls slept slightly longer than boys (5 min/ night; P = 0.03). Non-school day sleep was 16 min longer than school day sleep (P < 0.0001), with the difference increasing with age. Bedtimes got later with age (P < 0.0001), however there were no differences in bedtimes between boys and girls. Bedtimes occurred 34 min later on non-school days (P < 0.0001). Wake times were very similar across age groups on school days, but increased at the rate of 10 min/ year of age on non-school days. Wake times were similar for boys and girls, and occurred on average 82 min later on non-school days (P < 0.0001). Overall, 17% of school days and 20% of non-school days failed to meet the American Centers for Disease Control and Prevention sleep duration guidelines. Conclusions Normative sleep data will provide a valuable yardstick for health and education professionals when dealing with sleep-related issues.

Genetic and environmental influence on morningness-eveningness.

Article

Nov 1997

Sleep Patterns and Sexual Selection: An Evolutionary Approach

Article

Jun 2010
MANKIND QUART

Davide Piffer

Human sleep patterns differ across age groups and between males and females, and their association with age and gender suggest that they might have been the target of sexual selection during human evolutionary history. In this study, I test the hypothesis that a phase-delayed circadian phase is a sexually selected trait in humans. A short version of the Horne and Ostberg questionnaire and a questionnaire on sexual behaviour were administered to 134 males. A significant negative relationship was found between the MEQ score and the number of sexual partners among males, with evening types reporting more sexual partners than morning types. Findings support the hypothesis that evening preference in males is a sexually selected trait.

The Descent of Man

Book

Jan 1871

Charles Darwin

The Evolutionary Psychology of Extrapair Sex

Article

Mar 1997
EVOL HUM BEHAV

This study explored evolutionary hypotheses concerning extrapair sex (or EPCs: extrapair copulations). Based on recent notions about sexual selection, we predicted that (a) men's number of EPCs would correlate negatively with their fluctuating asymmetry, a measure of the extent to which developmental design is imprecisely expressed, and (b) men's number of times having been an EPC partner of a woman would negatively correlate with their fluctuating asymmetry. In a sample of college heterosexual couples, both hypotheses were supported. In addition, men's physical attractiveness independently predicted how often they had been an EPC partner. Women's anxious attachment style positively covaried with their number of EPC partners, whereas their avoidant attachment style negatively covaried with their number of EPC partners.

Costs and benefits of fat-free muscle mass in men: Relationship to mating success, dietary requirements, and native immunity

Article

Sep 2009
EVOL HUM BEHAV

On average, men have 61% more muscle mass than women (d=3), a sex difference which is developmentally related to their much higher levels of testosterone. Potential benefits of greater male muscle mass include increased mating opportunities, while potential costs include increased dietary requirements and decreased immune function. Using data on males aged 18–59 years from the third National Health and Nutrition Examination Survey and including other relevant variables, fat-free mass (FFM) and/or limb muscle volume (LMV) are significant predictors of the numbers of total and past-year self-reported sex partners, as well as age at first intercourse. On the cost side, FFM and LMV are strong positive predictors of daily energy intake and strong negative predictors of C-reactive protein and white blood cell count, measures of native immunity.

Sexual Selection

Book

Jan 1994
COPEIA

Malte Andersson

Validation of the full and reduced Composite Scale of Morningness

Article

Oct 2009
BIOL RHYTHM RES

Christoph Randler

Different self-report scales have been designed and developed to measure circadian preferences and there are attempts to develop shorter scales for research. The main aims of the present study were to provide further evidence for the validity of the full Composite Scale of Morningness (CSM), second, to develop a short scale of the CSM, and third, provide evidence for the short scale (rCSM). The full CSM was validated externally by self-report physical and cognitive peak performance, self-reported sleep–wake rhythm, and correlation with midpoint of sleep. Based on inter-item correlations and factor analysis, the final short scale was composed of Items 1, 2, 5, 6, 9, 10, 12 and labelled reduced CSM (rCSM). The rCSM contains two five-point-Likert items and five four-point-Likert items, and, thus, it ranges from 7 to 30 points as a possible total score. First analyses suggest a two factor structure. The rCSM showed good correlations with self-reported sleep–wake rhythm, midpoint of sleep, personality (conscientiousness) and the Morningness-Eveningness Questionnaire (MEQ). The scale was stable over approximately three months and was validated by subjective alertness ratings. The data obtained here suggest that the CSM in its full and reduced version is a valid instrument to assess circadian preference in both adult and adolescent samples.

Mimicry and the Evolution of Animal Communication

Article

Nov 1965
NATURE

Wolfgang Wickler

University students' motives for drinking alcohol are related to evening preference, poor sleep, and ways of coping with stress

Article

Oct 2011

Does evening circadian preference predict university students’ motives for drinking alcohol (i.e. social, enhancement, conformity, or coping motives)? Drinking to cope, which is associated with alcohol problems, may be more common in evening types because of their sleep problems and difficulties in dealing with stress. Two hundred and nineteen university students (M age = 21.80, SD = 6.80) completed online the Composite Scale of Morningness, the Drinking Motives Questionnaire Revised, the Sleep Quality Scale, the COPE measure of coping with stress, a measure of socially desirable responding, and gave information about gender and age. Evening preference was associated with greater use of all drinking motives, and with poorer sleep and poorer coping with stress. Multiple regression showed that drinking to cope was best predicted by poor sleep, social drinking, and avoidant coping with stress (R 2 = 0.45). Poor sleep and drinking to cope are a cause for concern because of possible reciprocal causality.

Morningness-eveningness in women around the transition through menopause and its relationship with climacteric complaints

Article

Dec 2010

One of the most striking facts is the transition to eveningness in adolescence around the age of 12–14 years which seems to be associated with pubertal development and with increasing sexual hormones. As women in their transition during menopause (at approx. 50 years) experience the contrary pattern, namely the reduction of sexual hormones, one should expect a turn towards morningness during these developmental stages. Women between 40 and 55 years, who were unaffected by hormone replacement therapy, gynaecological operations or hormonal contraceptives, participated in our study (pre-, peri- and post-menopausal stages). We found that women became more morning-orientated during the transition through menopause, which is considered an effect of hormonal changes rather than of age. Sleep problems increased from pre- to post-menopause while psychological complaints were highest during the peri-menopause. Further, we found a correlation between eveningness and psychological complaints, and a correlation between sleep problems and morningness. The presence of a partner was associated with higher morningness scores and earlier bed and rise times on weekends.

Sociobiology and Behavior

Article

Jan 1982
Man

David philip Barash

Morningness‐eveningness and behavioural problems in adolescents

Article

Nov 2010
SLEEP BIOL RHYTHMS

Individuals differ in their biological rhythms. Some persons are morning orientated, preferring morning hours for intellectual and physical activities, and others are evening orientated. Previous work on adults revealed correlations between this morningness–eveningness construct and different aspects of mental health and well-being; for example, depression and seasonal affective disorders were related to eveningness. We hypothesise that morningness–eveningness may be associated with behavioural variables as measured by Goodman's Strength and Difficulties Questionnaire (SDQ). 150 girls and 150 boys form German secondary schools participated in this study. We used the Composite Scale of Morningness (CSM) to assess chronotype and the SDQ to assess behavioural difficulties. CSM scores correlated positively with pro-social behaviour, and negatively with behavioural problems, hyperactivity, and the total problem score. These results suggest that adolescents with higher eveningness also have higher problems as measured by the SDQ.

An Evolutionary Approach to the Extraversion Continuum

Article

Jul 2005
EVOL HUM BEHAV

Daniel Nettle

Heritable individual differences in personality have not been fully accounted for within the framework of evolutionary psychology. This paper argues that personality axes such as extraversion can usefully be seen as dimensions of trade-off of different fitness costs and benefits. It is hypothesized that increasing extraversion will be associated with increasing mating success, but at the cost of either increased physical risk or decreased parenting effort. In a sample of 545 British adults, extraversion was a strong predictor of lifetime number of sexual partners. Male extraverts were likely to have extra-pair matings, whilst female extraverts were likely to leave existing relationships for new ones. On the cost side, increasing extraversion increased the likelihood of hospitalization for accident or illness. There was no direct evidence of reduced parenting effort, but extravert women had an increased likelihood of exposing their children to stepparenting. The study demonstrates that extraversion has fitness costs as well as benefits. Population variation related in the trait is unlikely to be eliminated by selection due to its polygenic nature, likely spatiotemporal variability in the optimal value, and possible status-and frequency-dependent selection.

IBM SPSS Amos 19 User's Guide

Article

James L. Arbuckle

Genetic and environmental influence on morningness–eveningness

Article

Nov 1998
PERS INDIV DIFFER

Little is known about the causes of the wide variability in circadian rhythms in humans. We present the first report of genetic influence on a circadian phenotype, the morningness-eveningness disposition. Two hundred and five pairs of adult monozygotic reared-together twins, and 55 pairs of adult monozygotic and 50 pairs of adult dizygotic reared-apart twins completed a morningness-eveningness questionnaire. Biometrical model-fitting showed that genetic variability accounted for about 54% of the total variance in morningness-eveningness; age contributed to 3% of the variance; and the remaining variance was explained by nonshared environmental influences and measurement error. Shared rearing environmental effects were not significant. The husband-wife correlation for morningness-eveningness was 0.25. This correlation appears to be due largely to assortative mating (the tendency of like to marry like) at the time of marriage rather than a consequence of cohabitation during marriage.

Personality, time of day and arousal

Article

Dec 1990
PERS INDIV DIFFER

Glenn Daniel Wilson

Sixty-one men and 50 women measured their own skin conductance hourly throughout one working day as well as recording drug intake and activities; they also completed the EPQ, I7 and Morningness-Eveningness questionnaires. As expected, self-reported Morning types showed higher skin conductance in the morning and Evening types in the evening. Introverts appeared as more highly aroused than extroverts, but particularly so in the morning; by midnight the two personality types had converged in skin conductance. Sociability, rather than impulsiveness, seemed to be the component of extraversion responsible for this interaction. Women showed higher conductance in the early morning, men in the afternoon and evening. Indications were that activity was determining arousal rather than the other way about, and that drug use was socially rather than neurologically motivated.

Measuring Personality in One Minute or Less: A 10-Item Short Version of the Big Five Inventory in English and German

Article

Feb 2007

To provide a measure of the Big Five for contexts in which participant time is severely limited, we abbreviated the Big Five Inventory (BFI-44) to a 10-item version, the BFI-10. To permit its use in cross-cultural research, the BFI-10 was developed simultaneously in several samples in both English and German. Results focus on the psychometric characteristics of the 2-item scales on the BFI-10, including their part-whole correlations with the BFI-44 scales, retest reliability, structural validity, convergent validity with the NEO-PI-R and its facets, and external validity using peer ratings. Overall, results indicate that the BFI-10 scales retain significant levels of reliability and validity. Thus, reducing the items of the BFI-44 to less than a fourth yielded effect sizes that were lower than those for the full BFI-44 but still sufficient for research settings with truly limited time constraints.

Gender differences in morningness–eveningness assessed by self-report questionnaires: A meta-analysis

Article

Jan 2007
PERS INDIV DIFFER

Christoph Randler

Gender differences in circadian typology and in biological rhythms have been revealed by using biological measurements but results based on self-report questionnaires are inconclusive. I applied meta-analytical tools to examine gender differences in morningness. I searched different databases for studies presenting values for morningness in males and females. Fifty-two studies were identified from which 11 used the composite scale of morningness CSM, 29 the morningness–eveningness-questionnaire MEQ, and eight the morning/evening questionnaire M/E. Most studies (51.9%) were carried out with students. There was no significant publication bias. Taken together, the meta-analysis suggests a weak but significant effect of gender on morningness (overall effect size E = 0.097 under a fixed effects model and E = 0.0845 under a random effects model). Girls and women were significantly more morning oriented than boys and men. Further, standard deviations of mean age of the subjects had a significant effect on effect sizes suggesting that large standard deviations, and thus a large age range within a study, produced smaller effect sizes. Focusing on student samples revealed higher effect sizes (E = 0.196). With regard to the different questionnaires, the CSM produced the largest effect sizes, followed by the MEQ.

Relationship of Chronotype to Sleep, Light Exposure, and Work-Related Fatigue in Student Workers

Article

Apr 2012
CHRONOBIOL INT

Students who work during the school year face the potential of sleep deprivation and its effects, since they have to juggle between school and work responsibilities along with social life. This may leave them with less time left for sleep than their nonworking counterparts. Chronotype is a factor that may exert an influence on the sleep of student workers. Also, light and social zeitgebers may have an impact on the sleep-related problems of this population. This study aimed to document sleep, light exposure patterns, social rhythms, and work-related fatigue of student workers aged 19-21 yrs and explore possible associations with chronotype. A total of 88 student workers (mean ± SD: 20.18 ± .44 yrs of age; 36 males/52 females) wore an actigraph (Actiwatch-L; Mini-Mitter/Respironics,Bend, OR) and filled out the Social Rhythm Metric for two consecutive weeks during the school year. Also, they completed the Morningness-Eveningness Questionnaire (MEQ), Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and Occupational Fatigue Exhaustion/Recovery Scale (OFER). Repeated and one-way analyses of variance (ANOVAs), Pearson's chi-square tests, and correlation coefficients were used for statistical comparisons. Subjects slept an average of 06:28 h/night. Actigraphic sleep parameters, such as sleep duration, sleep efficiency, wake after sleep onset, and sleep latency, did not differ between chronotypes. Results also show that evening types (n = 17) presented lower subjective sleep quality than intermediate types (n = 58) and morning types (n = 13). Moreover, evening types reported higher levels of chronic work-related fatigue, exhibited less regular social rhythms, and were exposed to lower levels of light during their waking hours (between 2 and 11 h after wake time) as compared to intermediate types and morning types. In addition, exposure to light intensities between 100 and 500 lux was lower in evening types than in intermediate types and morning types. However, bright light exposure (≥ 1000 lux) did not differ between chronotypes. In conclusion, results suggest that student workers may constitute a high-risk population for sleep deprivation. Evening types seemed to cope less well with sleep deprivation, reporting poorer sleep quality and higher levels of work-related fatigue than intermediate types and morning types. The higher chronic work-related fatigue of evening types may be linked to their attenuated level of light exposure and weaker social zeitgebers. These results add credence to the hypothesis that eveningness entails a higher risk of health-impairing behaviors.

Sleep quality and diurnal preference in a sample of young adults: Associations with 5HTTLPR, PER3, and CLOCK 3111

Article

Sep 2011
AM J MED GENET B

Research investigating associations between specific genes and individual differences with regards to the quality and timing of sleep has primarily focussed on serotonin-related and clock genes. However, there are only a few studies of this type and most of those to date have not considered the possibility of gene-environment interaction. Here, we describe associations between sleep quality and diurnal preference and three functional polymorphisms: 5HTTLPR, PERIOD3, and CLOCK 3111. Furthermore, we assessed whether associations between genotypes and sleep phenotypes were moderated by negative life events-a test of gene-environment interaction. DNA from buccal swabs was collected from 947 individuals [mean age = 20.3 years (SD = 1.77), age range = 18-27 years; 61.8% female] and genotyped for the three polymorphisms. Participants completed the Pittsburgh Sleep Quality Index and the Morningness-Eveningness Questionnaire. There was a significant main effect of 5HTTLPR on sleep quality, indicating that "long-long" homozygotes experienced significantly poorer sleep quality (mean = 6.35, SD = 3.36) than carriers of at least one "short" allele (mean = 5.67, SD = 2.96; β = -0.34, P = 0.005). There were no main effects of 5HTTLPR on diurnal preference; no main effects of PERIOD3 or CLOCK on sleep quality or diurnal preference; and no significant interactions with negative life events. The main effect of the "long" 5HTTLPR allele contradicts previous research, suggesting that perhaps the effects of this gene are heterogeneous in different populations. Failure to replicate previous research in relation to PERIOD3 and CLOCK concurs with previous research suggesting that the effects of these genes are small and may be related to population composition.

Human Diurnal Preference and Circadian Rhythmicity are Not Associated with the CLOCK 3111C/T Gene Polymorphism

Article

Jun 2011
J BIOL RHYTHM

Genetic association studies of the CLOCK 3111C/T polymorphism and diurnal preference have yielded conflicting results since the first report that the 3111C allele was associated with eveningness. The goal of the present study was to investigate the association of this polymorphism with diurnal preference and circadian physiology in a group of 179 individuals, by comparing the frequency of the 3111C allele to diurnal preference, habitual sleep timing, circadian phase markers, and circadian period. We did not find a significant association between this allele and morningness/eveningness or any circadian marker.

Influence of Circadian Typology on Drug Consumption, Hazardous Alcohol use, and Hangover Symptoms

Article

May 2011
CHRONOBIOL INT

Few studies have focused on the influence of circadian typology on drug use, and none has considered the use of illegal drugs and hazardous alcohol consumption. This study analyzes the influence of circadian typology on several types of drug consumption (habitual or sporadic), hangover symptoms (past 12 mos), and, more specifically, hazardous alcohol consumption of young adults. Five hundred seventeen university students (173 males), between 17 and 30 yrs of age, answered the Composite Scale of Morningness (CSM), the Alcohol Use Disorders Identification Test (AUDIT), and a self-referred questionnaire on drug consumption during the previous month and on the prevalence of different hangover symptoms during the previous year. Our results confirm a higher prevalence of consumption of addictive substances, both legal (nicotine and cola drinks) and illegal (cannabis and ecstasy), in evening- compared to morning- and neither-type subjects (p < .001 in all cases). Evening-type subjects also obtained a higher total score on the AUDIT (p < .001) and showed a greater prevalence in the subscales of potential alcohol problems (p < .02), as well as more frequent different hangover symptoms (learning difficulties, thirst, tiredness, headaches, sensorial hypersensitivity, anxiety, and irritability; p < .04 in all cases) compared with morning- and neither-type subjects, except for sensorial hypersensitivity and anxiety, for which the evening-type did not differ from the neither-type. Our results provide substantial evidence that the evening circadian typology is a risk factor for the development of drug consumption and that it should be taken into account both in preventive and treatment approaches. Moreover, the data regarding hazardous alcohol use and hangover symptoms emphasize the need to include circadian typology in future studies on the pattern of heavy episodic drinking.

Changes in Circadian Rhythms during Puberty in Rattus Norvegicus: Developmental Time Course and Gonadal Dependency

Article

Mar 2011
HORM BEHAV

During puberty, humans develop a later chronotype, exhibiting a phase-delayed daily rest/activity rhythm. The purpose of this study was to determine: 1) whether similar changes in chronotype occur during puberty in a laboratory rodent species, 2) whether these changes are due to pubertal hormones affecting the circadian timekeeping system. We tracked the phasing and distribution of wheel-running activity rhythms during post-weaning development in rats that were gonadectomized before puberty or left intact. We found that intact peripubertal rats had activity rhythms that were phase-delayed relative to adults. Young rats also exhibited a bimodal nocturnal activity distribution. As puberty progressed, bimodality diminished and late-night activity phase-advanced until it consolidated with early-night activity. By late puberty, intact rats showed a strong, unimodal rhythm that peaked at the beginning of the night. These pubertal changes in circadian phase were more pronounced in males than females. Increases in gonadal hormones during puberty partially accounted for these changes, as rats that were gonadectomized before puberty demonstrated smaller phase changes than intact rats and maintained ultradian rhythms into adulthood. We investigated the role of photic entrainment by comparing circadian development under constant and entrained conditions. We found that the period (τ) of free-running rhythms developed sex differences during puberty. These changes in τ did not account for pubertal changes in entrained circadian phase, as the consolidation of activity at the beginning of the subjective night persisted under constant conditions in both sexes. We conclude that the circadian system continues to develop in a hormone-sensitive manner during puberty.

Sex and searching for children among Aka foragers and Ngandu farmers of Central Africa

Article

Jan 2010
Afr Stud Monogr

Few systematic studies exist on the sexual behavior of hunter-gatherers and rural central Africans. This study examines the reasons for having sex, the frequency of sex (coitus) per night, sexual practices during the post-partum sex taboo, and beliefs and practices regarding homosexuality, masturbation, the use of sexual stimulants and a variety of other sexual behaviors. Thirty-fi ve Aka and twenty-one Ngandu adults who were or had been married were interviewed. For adults 18–45 years of age, the average frequency of sex per night was about three times among the Aka and two times among the Ngandu. Age had no impact on the frequency of sex per night. Aka averaged two days and Ngandu averaged three days between days with sexual activity. Aka and Ngandu cultural models or reasons for having frequent sex emphasized their desire for children rather than pleasure. Homosexuality and masturbation were rare or nonexistent in both groups. Aka men either did not believe in the post-partum taboo or if they had this belief they did not seek out other women during this period; almost all Ngandu men said they believed in the taboo but did not adhere to it and sought out other women. Aka men had the greatest knowledge and most frequent use of plants as sexual stimulants.

Salivary Testosterone, cortisol, and Progesterone: two-week stability, interhormone correlations, and effects of time of day, menstrual cycle, and oral contraceptive use on steroid hormone levels

Article

Oct 2009

With salivary assessment of steroid hormones increasing, more work is needed to address fundamental properties of steroid hormone levels in humans. Using a test-retest design and radioimmunoassay assessment of salivary steroids, we tested the reliability of testosterone, cortisol, and progesterone levels across two weeks, as well as the effects of oral contraceptives, menstrual cycle phase, and time of day on steroid hormone levels. Testosterone and cortisol were found to be highly reliable in both sexes. Progesterone was found to be reliable after collapsing across sex. Oral contraceptive use was associated with lower levels of testosterone, but did not affect cortisol. Contrary to expectations, oral contraceptives also did not affect progesterone. Menstrual cycle was found to affect levels of progesterone, but not testosterone or cortisol. Time of day had an effect on cortisol, on progesterone only at one testing time, and no effect on testosterone. We explored the interhormone correlations among testosterone, progesterone, and cortisol. All three hormones were positively correlated with one another in men. In women, progesterone was positively correlated with testosterone and cortisol, but testosterone and cortisol were uncorrelated.

In Sync with the Family: Children and Partners Influence the Sleep-Wake Circadian Rhythm and Social Habits of Women

Article

May 2009
CHRONOBIOL INT

Different factors have been proposed to influence morningness-eveningness, biological rhythms, and sleep-wake cycles, but few studies focused on the influence of social habits. Here, we focus on the influence of children and partners on the social habits of women at different stages of their lives and on synchronization within the family. One hundred and seventy-nine women participated in the study and were allocated into four groups: women without children, pregnant women without children, pregnant women with children, and non-pregnant mothers. Morningness was predicted by the presence of children, and earlier chronotype was predicted by the presence of children, pregnancy, and age. Average sleep duration was longest in pregnant women. The presence of children was responsible for a difference in rise times of approximately 1.5 h on the weekend. Subjective sleep-onset latencies were shortest in women with children. The synchrony between partners (husband/wife) was 0.46 in women without children, 0.79 in pregnant women, 0.40 in women with children, and 0.56 between mother and child. Partners' chronotypes were highly correlated, as were those of mother and child. This study suggests children have a strong influence on their mother's lifestyle and sleep-wake rhythm, far beyond the first months of life, and that children are a more important social factor than the male partner.

Depressive symptomatology is influenced by chronotypes

Article

Apr 2009

Rhythm disturbances are a frequent clinical manifestation of depression. In recent years a possible relationship between depression and chronotypes has emerged. Specifically eveningness has been proposed as vulnerability factor. The aim of this study was to describe sleep features of depressed patients according to chronotypes and to explore possible associations with the clinical features of depressive episodes. 100 patients diagnosed with Major Depressive Disorder according to the Mini International Neuropsychiatric Interview (MINI) were included (age: 34+/-11.74, range: 18-60 years; female/male:79/21). At admission the Hamilton Rating Scale for Depression (HRSD) was administered. Patients were also administered the Morningness-Eveningness Questionnaire (MEQ), the Epworth Sleepiness Scale, the Athens Insomnia Scale and the Pittsburgh Sleep Quality Index. According to MEQ scores patients were classified in three groups: a) eveningness (n=18), b) neither (n=61) and c) morningness type (n=21). The age was different among chronotypes, being morningness-type patients older. The eveningness-type group showed higher scores in suicidal thoughts, more impaired work and activities, higher paranoid symptoms, higher scores on the anxiety cluster (HRSD), while the morningness-type group showed lower proportion of melancholic symptoms (MINI). We did not find association between sleep parameters and specific chronotypes. The relatively small sample size and the concurrent assessment of chronotypes and depression may have biased our findings. Our data suggest the idea that chronotypes have an impact on depressive episodes features, with higher severity for the eveningness-type.

Morningness-Eveningness Comparison in Adolescents from Different Countries around the World

Article

Dec 2008
CHRONOBIOL INT

Christoph Randler

Very few studies have focused on differences in chronotype around the globe. In this study, morningness-eveningness was measured using the Composite Scale of Morningness and the midpoint of sleep on free days (corrected for sleep debt, MSF(sc)) in adolescents of sixteen German schools abroad, dispersed all over the world, and for comparison pupils attending German schools. There was no influence of duration of residence in the respective locality, and sex differences were weak. Age correlated negatively with morningness. A significant influence of climate zone (temperate, subtropics, tropics) was found, with adolescents in the subtropics being the latest chronotypes, and an interaction of agexclimate zone was identified. Significant associations between chronotype and longitude and latitude were identified within the time zone of central Europe. Adolescents were found to be more morning oriented both toward the East and North. The results indicate that climate, longitude, and latitude contribute to chronotype.

Sex Difference in Sleep‐Time Preference and Sleep Need: A Cross‐Sectional Survey among Italian Pre‐Adolescents, Adolescents, and Adults

Article

Oct 2008
CHRONOBIOL INT

The aim of this study was to examine sex differences in sleep-time preference by age among Italian pre-adolescents, adolescents, and adults. The final sample consisted of 8,972 participants (5,367 females and 3,605 males) from 10 to 87 yrs of age. To assess preferred sleep habits, we considered the answers to the open-ended questions of the Morningness-Eveningness Questionnaire (MEQ). In agreement with previous studies, we found that sleep-time preference started to shift toward eveningness from the age of 13 yrs. Females reached their peak in eveningness earlier (about 17 yrs of age) than males (about 21 yrs of age). Thereafter, the ideal sleep-time preference advanced in men and women with increasing age. Females presented a more significant advanced sleep phase than males only during the years when sexual hormones are typically active. Moreover, females reported a longer ideal sleep duration than males across all age groups examined, except in over 55 yrs one.

Gender differences in strength and muscle fiber characteristics

Article

Mar 1993
Eur J Appl Physiol Occup Physiol

Strength and muscle characteristics were examined in biceps brachii and vastus lateralis of eight men and eight women. Measurements included motor unit number, size and activation and voluntary strength of the elbow flexors and knee extensors. Fiber areas and type were determined from needle biopsies and muscle areas by computerized tomographical scanning. The women were approximately 52% and 66% as strong as the men in the upper and lower body respectively. The men were also stronger relative to lean body mass. A significant correlation was found between strength and muscle cross-sectional area (CSA; P < or = 0.05). The women had 45, 41, 30 and 25% smaller muscle CSAs for the biceps brachii, total elbow flexors, vastus lateralis and total knee extensors respectively. The men had significantly larger type I fiber areas (4597 vs 3483 microns2) and mean fiber areas (6632 vs 3963 microns2) than the women in biceps brachii and significantly larger type II fiber areas (7700 vs 4040 microns2) and mean fiber areas (7070 vs 4290 microns2) in vastus lateralis. No significant gender difference was found in the strength to CSA ratio for elbow flexion or knee extension, in biceps fiber number (180,620 in men vs 156,872 in women), muscle area to fiber area ratio in the vastus lateralis 451,468 vs 465,007) or any motor unit characteristics. Data suggest that the greater strength of the men was due primarily to larger fibers. The greater gender difference in upper body strength can probably be attributed to the fact that women tend to have a lower proportion of their lean tissue distributed in the upper body.(ABSTRACT TRUNCATED AT 250 WORDS)

Self-report of circadian type reflects the phase of melatonin rhythm

Article

Jun 1999
BIOL PSYCHOL

This study examined the relationship between circadian rhythm characteristics of the pineal hormone melatonin and individual differences in circadian type and mood. 95 healthy young men and 22 women were assessed each hour (00:00-07:00 h) for blood levels of melatonin throughout one night in the laboratory. Each subject was assessed for circadian type (morning, afternoon, or evening type) and morning mood (PANAS). Circadian type was strongly related to the melatonin acrophase but not to amplitude or time of year of assessment. Also, morning types evidenced a more rapid decline in melatonin levels after the peak than did evening types. Evening types were younger than were morning types. Female morning types reported more positive affect upon waking than did female afternoon or evening types. Males showed no such discrimination. Age was related to both melatonin acrophase and circadian type but did not explain the relationship between them. The results replicate and extend findings on circadian type and psychological and physiological variables.

A marker for the end of adolescence

Article

Jan 2005
CURR BIOL

Between childhood and adulthood, we go through puberty and adolescence. While the end of puberty is defined as the point of cessation of bone growth (epiphyseal closure; girls: 16 y; boys: 17.5 y), the end of adolescence (∼19 y) is defined less clearly, by a mixture of physical, psychological, social, and mental measures [1]. One conspicuous property of adolescence is the apparently unsaturable capacity to stay up late and to sleep in. Investigating ‘chronotypes’ we observed an abrupt change in the timing of sleep at around the age of 20 and propose this change as the first biological marker of the end of adolescence.

Eveningness is related to men’s mating success

Abstract and Figures

No full-text available

Recommended publications

Chronotype and Social Behavior