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S H O R T R E P O R T Open Access
Do the Morningness-Eveningness
questionnaire and Munich ChronoType
questionnaire change after morning light
treatment?
Helen J. Burgess
1*
, Fumitaka Kikyo
1
, Zerbrina Valdespino-Hayden
2
, Muneer Rizvydeen
1
, Momoko Kimura
1
,
Mark H. Pollack
2
, Stevan E. Hobfoll
1
, Kumar B. Rajan
3
, Alyson K. Zalta
1,2
and John W. Burns
1
Abstract
The Morningness-Eveningness Questionnaire (MEQ) and Munich ChronoType Questionnaire (MCTQ) are sometimes
used to estimate circadian timing. However, it remains unclear if they can reflect a change in circadian timing after a
light treatment. In this study, 31 participants (25–68 years) completed both questionnaires before and after a 13–28 day
morning light treatment. The dim light melatonin onset (DLMO), a physiological marker of circadian timing, was also
assessed in a subsample of 16 participants. The DLMO phase advanced on average by 47 min (p<0.001).TheMEQ
score increased by 1.8 points (p= 0.046). The MSFsc measure derived from the MCTQ advanced by 8.7 min (p=0.17).
The shift towards morningness observed in both questionnaires correlated with the phase advance observed in the
DLMO (MEQ r=−0.46, p=0.036;MSFscr=0.81,p< 0.001). Results suggest that these circadian questionnaires can
change in response to a light treatment, indicating they can reflect underlying changes in circadian timing.
Trial registration: Clinicaltrials.gov NCT02373189 retrospectively registered 2/26/15; NCT03513848 retrospectively
registered 5/2/18.
Keywords: Circadian, Human, Light, Melatonin, Sleep
Introduction
The dim light melatonin onset (DLMO) is the most reli-
able measure of central circadian timing in humans
(Lewy et al. 1999; Klerman et al. 2002). The onset of the
secretion of melatonin, which is tightly controlled by the
central circadian clock (suprachiasmatic nucleus, SCN)
(Moore 1996), typically begins 2–3 h before habitual
sleep onset (Burgess and Fogg 2008). The melatonin
rhythm must be measured in dim light, as it is sup-
pressed by light (Lewy et al. 1980). The DLMO can usu-
ally be obtained from saliva samples, collected every
half-hour or hour, in the 6 h window before habitual
sleep onset (Burgess and Fogg 2008). However, there are
significant disadvantages in measuring the DLMO: it re-
quires staff to assist in the collection and processing of
samples, significant participant effort, and the melatonin
assay can be costly (~$14 per sample). For these reasons,
there remains considerable interest in estimating circa-
dian timing with questionnaires.
Two such questionnaires include the Morningness-
Eveningness Questionnaire (MEQ) (Horne and Ostberg
1976), and the Munich ChronoType Questionnaire
(MCTQ) (Roenneberg et al. 2003). As we reviewed pre-
viously (Kantermann et al. 2015), the MEQ includes 19
questions that ask people to consider their “feeling best”
rhythms and indicate preferred clock time blocks for
sleep and engagement in various hypothetical activities
(e.g. physical exercise, tests, work), in addition to asses-
sing morning alertness, morning appetite, evening tired-
ness and alarm clock dependency. MEQ scores can
range from 16 to 86, with lower scores indicating
* Correspondence: Helen_J_Burgess@rush.edu
1
Biological Rhythms Research Laboratory, Department of Behavioral Sciences,
Rush University Medical Center, Chicago, IL, USA
Full list of author information is available at the end of the article
Slee
p
Science and Practic
e
© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Burgess et al. Sleep Science and Practice (2018) 2:12
https://doi.org/10.1186/s41606-018-0031-1
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
eveningness or later circadian timing, and higher scores
indicating morningness or earlier circadian timing. By
contrast, the MCTQ focuses primarily on sleep timing
and via 14 questions, assesses the regularity of one’s
work schedule, number of workdays per week, sleep tim-
ing on workdays and work-free days, and alarm clock
use on workdays and work-free days. Circadian timing is
estimated as the midpoint of sleep on work-free days
minus half of the difference between sleep duration on
work-free days and average sleep duration of the week to
control for sleep debt (midpoint of sleep on work-free
days, sleep corrected, referred to from here on as
MSFsc). Importantly, the MSFsc should only be consid-
ered valid when individuals report not using an alarm
clock on work-free days (Roenneberg et al. 2012). We
and others have reported that the estimates of circadian
timing generated from these questionnaires, do indeed
correlate significantly with the DLMO (MEQ and
DLMO rs = −0.40 to −0.70; MSFsc and DLMO rs = 0.54
to 0.68; (Kitamura et al. 2014, Kantermann et al. 2015).
A related, but to date unanswered, question is whether
these questionnaires are sensitive enough to reflect an
underlying change in circadian timing following a light
treatment. If they do, this would further support their
use as potential estimators of circadian timing when dir-
ect measurement of the DLMO is not feasible. Thus, the
objective of this study was to examine these circadian
questionnaires before and after a bright light treatment.
Materials and methods
Our sample consisted of 31 participants (23 males, 8 females,
mean age 45.9 ± 13.7 years, mean BMI 30.3 ± 6.0 kg/m
2
, 45%
Non-Hispanic African American, 32% Non-Hispanic White,
19% Hispanic White, 3% other) who were recruited from
internet advertising (e.g. craigslist.com). The majority was
not working (68% not working, 26% part-time workers, 6%
full-time workers), none had engaged in shift work in at least
the past month, and all passed a urine drug test and alcohol
breathalyzer test. The sample was derived from two separate
clinical trials that tested the mood altering effects of a
self-administered morning bright light treatment adminis-
tered at home for 13–28 days. In both studies, the 1 h light
treatment was scheduled to start each morning at the sub-
ject’s average wake time (derived from a baseline week of
wrist actigraphy collected just prior to the start of the light
treatment), or up to 1 h earlier to accommodate morning so-
cial responsibilities (e.g. work, child care). In the first trial,
23 U.S. military veterans with chronic low back pain received
morning bright light from two broad-spectrum white light
boxes that research staff set up in their homes (33 × 18 ×
55 cm, EnergyLight HF3318/60, Philips, Inc., generated >
3000 lx at subjects’eyes). The light treatment was scheduled
for 13 consecutive mornings (NCT02373189 on clinical-
trials.gov). Light readings from photosensors attached to the
light boxes were checked against light readings on each sub-
ject’s wrist monitor (Actiwatch Spectrum, Philips, Inc) to
monitor adherence to the light treatment. In the second trial,
8 subjects with probable post-traumatic stress disorder
(Post-Traumatic Stress Disorder Checklist for DSM-5 score >
33, (Weathers et al. 2013, Bovin et al. 2016)) received morn-
ing light from a wearable light device, the Re-timer (20 ×
14 × 5.5 cm, Re-time, Inc., Australia, generated ~ 500 lx at
subjects’eyes, with peak wavelength of ~ 500 nm). The
Re-timer was individually adjusted to each subject to
optimize the light treatment, which was scheduled for 28
consecutive mornings (NCT03513848 on clinicaltrials.gov).
Light and activity readings from a monitor (Actiwatch
Spectrum, Philips, Inc) attached to the inside of the Re-timer
were used to monitor adherence to the light treatment. All
subjects included in this report received the morning light
treatment on at least 80% of the assigned mornings.
The MEQ and MCTQ were measured at the end of
the baseline week, which was also the day before the
start of the light treatment. They were then re-measured
on the day of the last light treatment, after the light
treatment had concluded. In the veteran trial, a validated
home saliva collection kit (Burgess et al. 2015; Burgess
et al. 2016) was used to assess the dim light melatonin
onset (DLMO) at the same pre and post-treatment time
points. Saliva samples were collected every half hour for
6 h in dim light (< 50 lx), starting 6 h before average
sleep onset time. All subjects refrained from caffeine and
alcohol in at least the 24 h before saliva collection, and
refrained from non-steroidal anti-inflammatory drugs
for at least 72 h before saliva collection. No participants
were taking beta-blockers or exogenous melatonin.
Melatonin levels were derived from the saliva samples
by Solidphase Inc. (Portland, ME), with a direct radio-
immunoassay using standard Buhlmann kits with assay
sensitivity of 0.5 pg/ml, intra and interassay CV < 7.5%
at 3 pg/ml. The DLMO was calculated as the clock time
(with linear interpolation) when the melatonin concen-
tration exceeded the mean of 3 low consecutive daytime
values plus twice the standard deviation of these points
(Voultsios et al. 1997). This low threshold more closely
tracks the initial rise of melatonin, when the SCN
triggers the release of melatonin from the pineal gland
(Molina and Burgess 2011). The DLMOs for seven
veterans were not valid due to low levels of melatonin
(< 5 pg/ml) or erratic melatonin profiles. The DLMO
was not assessed in the PTSD trial. The Rush University
Medical Center Institutional Review Board approved
both study protocols, which followed the principles of
the Declaration of Helsinki. All subjects gave written in-
formed consent prior to participation. The changes in
DLMO, MEQ and MSFsc (derived from the MCTQ)
were analyzed with a paired samples t-test. As morning
light is well recognized to cause circadian phase
Burgess et al. Sleep Science and Practice (2018) 2:12 Page 2 of 5
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
advances, an increase in morningness was predicted, and
a one-tailed p-value of < 0.05 was used to determine
statistical significance.
Results
The variables were normally distributed. The changes in
the DLMO, MEQ score and MSFsc from pre- to post-
light treatment are shown in Fig. 1. On average, the
DLMO significantly phase advanced by 47 min (p<0.001,
n= 16, d = 1.49). The MEQ score significantly increased
by 1.8 points (p=0.046, n= 31, d = 0.32), reflecting more
morningness after the morning light treatment. The
MSFsc advanced by 8.7 min, but this was not statistically
significant (p= 0.17, n = 31, d = 0.17). Nine subjects re-
ported using alarm clocks on their non-work days. With
those subjects removed the advance in MSFsc increased
to 14.4 min, but this change was still not significant
(p=0.12, n= 22, d = 0.25). Overall, the phase advance in
the DLMO correlated with an increase in morningness on
both questionnaires (MEQ r=−0.46, p=0.036; MSFsc
r=0.81,p< 0.001, n = 16).
Discussion
These results indicate that the MEQ and MCTQ ques-
tionnaires can reflect an increase in morningness follow-
ing a morning light treatment. The MEQ score increased
significantly, reflecting more morningness, and also corre-
lated with the phase advance in the DLMO. The MSFsc
derived from the MCTQ did not significantly change with
the light treatment, but the increase in morningness did
correlate significantly with the degree of circadian phase
advance observed in the DLMO. Thus these results fur-
ther support the use of these circadian questionnaires as
potential estimators of circadian timing when direct meas-
urement of the DLMO is not feasible. Contrary to other
sleep questionnaires, the MEQ and MCTQ (at least the
earlier version we used in this study) do not have any time
frame in their instructions for completion, such as “in the
past week”which is used in the Insomnia Severity Index
(Bastien et al. 2001)and“during the past month only”
which is used in the Pittsburgh Sleep Quality Index
(Buysse et al. 1989). This lack of time reference may have
reduced the ability to detect differences in the MEQ score
and MSFsc, with assessments only 2–4 weeks apart. The
greater sensitivity of the MEQ to the morning light treat-
ment may be due to the questions in the MEQ assessing a
broader range of activities beyond sleep, including for ex-
ample people’s“feeling best”rhythms and preferred clock
times for engagement in various hypothetical activities
(e.g. physical exercise, tests, work), in addition to assessing
morning alertness, morning appetite, evening tiredness
and alarm clock dependency. By contrast, the MCTQ fo-
cuses primarily on sleep timing and alarm clock use, and
responses may be more constrained by perceived societal
norms surrounding usual sleep times. Additionally, even
though the majority of our sample was not working, al-
most a third of subjects reported using an alarm clock on
their work-free days, which may reflect other non-work
social responsibilities. It remains unclear if these subjects
were reporting the setting of an alarm on these days, or
the actual waking to an alarm clock on those days. Fur-
ther, use of an alarm clock on work-free days technically
Fig. 1 The changes in MSFsc, MEQ score, and DLMO observed in each
individual subject before and after a 13 or 28 day morning light
treatment. The results for an individual subject are connected by a line.
The mean and standard deviation at each time point is also shown
Burgess et al. Sleep Science and Practice (2018) 2:12 Page 3 of 5
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
invalidates the MSFsc (Roenneberg et al. 2012), indicating
the higher potential for missing data when using the
MCTQ than when using the MEQ.
There are several limitations to our study. We were
not able to assess DLMO in all subjects, and therefore
cannot verify a significant circadian phase advance oc-
curred in the entire sample. Nonetheless, the subsample
of 16 subjects revealed a statistically significant phase
advance of ~ 50 min in response to the morning bright
light, which is remarkably consistent with the phase ad-
vance seen in the phase response curve to 1 h of light,
when administered at average wake time (~ 14 h after
the DLMO, Figure 3 in (St. Hilaire et al. 2012)). Add-
itionally, the Re-timer has been shown to elicit phase
shifts in the DLMO (Lovato and Lack 2016). Given that
objectively measured adherence to the light treatment in
both trials was reasonable, it is likely that on average the
entire sample phase advanced in response to the morn-
ing light treatment. Indeed the increase of ~ 2 points in
the MEQ observed in the full sample, was similar to that
observed in the subsample in which the DLMO was
measured. We also note that we have no control group,
and thus no measure of the natural fluctuations in these
circadian questionnaires over time. We also recognize that
our sample size was small, and therefore our analyses were
underpowered. We encourage other researchers assessing
the circadian effects of light treatment to consider adminis-
tering these circadian questionnaires both before and after
a light treatment to further explore the sensitivity of these
questionnaires in larger samples. To our knowledge this is
rarely done in light treatment studies. Future work should
also examine these relationships in larger non-clinical sam-
ples (Di Milia et al. 2013), as our sample is not necessarily
representative of the general population and was largely
male. It would also be interesting to determine if circadian
phase shifts due to other non-photic stimuli, such as ex-
ogenous melatonin, could also significantly shift the scores
derived from these circadian questionnaires.
Abbreviations
BMI: Body mass index; DLMO: Dim light melatonin onset; MCTQ: Munich
ChronoType Questionnaire; MEQ: Morningness-Eveningness Questionnaire;
MSFsc: Midpoint of sleep on work-free days sleep corrected; PTSD: Post-
traumatic stress disorder; SCN: Suprachiasmatic nucleus
Acknowledgements
We thank Karyna Bravo, Morgan Corich, Joshua Dein, Aahad Kahn, Catherine
Keefner, Mary Kennedy, Athanasios Kondilis, Othon Nunez-Montelongo, Daria
Orlowska, Philip Sanchez, Monica Thomas, Marie Vallido, Amanda Vatinno,
and Denise Zou for their assistance with data collection. Research reported
in this publication was supported by the National Center for Complementary
and Integrative Health of the National Institutes of Health under Award
Number R34AT008347, and by internal funds provided by the Department of
Psychiatry at Rush University Medical Center. Alyson Zalta’s contribution was
supported by a training grant from the National Institute of Mental Health
(K23 MH103394). The content is solely the responsibility of the authors
and does not necessarily represent the official views of the National
Institutes of Health.
Competing interests
Dr. Burgess is a consultant for Natrol, LLC. Dr. Pollack reports personal fees
from Aptinyx, Bracket Global, Palo Alto Health Sciences, grants from Janssen,
outside the submitted work. In addition, Dr. Pollack has a patent SIGHA,
SAFER interviews with royalties paid and Equity in Argus, Doyen Medical,
Mensante Corporation, Mindsite, Targia Pharmaceuticals. All other authors
report no conflicts of interest.
Authors’contributions
All authors read and approved the final manuscript.
Publisher’sNote
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Author details
1
Biological Rhythms Research Laboratory, Department of Behavioral Sciences,
Rush University Medical Center, Chicago, IL, USA.
2
Department of Psychiatry,
Rush University Medical Center, Chicago, IL, USA.
3
Department of Internal
Medicine, Rush University Medical Center, Chicago, IL, USA.
Received: 12 July 2018 Accepted: 22 August 2018
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