Owls, larks, swifts, woodcocks and they are not alone: A historical review of methodology for multidimensional self-assessment of individual differences in sleep-wake pattern

Morning affect or sleep inertia? Comparing the constructs and their measurement

The construct of Morning Affect (MA; alertness upon awakening/time required to feel fully awake) emerged from exploratory factor analysis of morningness-eveningness questionnaires, and while it has been equated with morningness-eveningness preference it has much conceptual overlap with sleep inertia (SI; the transitional state between sleep and being fully awake). The current study compared questionnaire measures of these constructs to help clarify their inter-relationships. A volunteer sample of 453 students at an English-medium university in China completed an online survey including the Sleep Inertia Questionnaire (SIQ), the Morningness-Eveningness-Stability-Scale-improved (MESSi), with subscales for MA, Eveningness, and Distinctness (amplitude of diurnal variation), and the reduced Morningness-Eveningness Questionnaire (rMEQ). Measures of depression, sleep quality, mindfulness, and personality were also included. Exploratory factor analysis of the SIQ, MESSi, and rMEQ items revealed seven factors: Cognitive, Emotional, and Physiological SI, Responses to SI (including one MA item), and Duration of SI (one SIQ item, 3/5 MA items, and one rMEQ item); Morningness-Eveningness (MESSi Eveningness items, plus 3/5 rMEQ items); Distinctness (3/5 MESSi items). These results suggest that Morning Affect may be better characterised as a general measure of sleep inertia, and may contribute to ongoing development/refinement of questionnaire measures of circadian functioning.

Beyond sleep: A multidimensional model of chronotype

Chronotype can be defined as an expression or proxy for circadian rhythms of varied mechanisms, for example in body temperature, cortisol secretion, cognitive functions, eating and sleeping patterns. It is influenced by a range of internal (e.g., genetics) and external factors (e.g., light exposure), and has implications for health and well-being. Here, we present a critical review and synthesis of existing models of chronotype. Our observations reveal that most existing models and, as a consequence, associated measures of chronotype have focused solely or primarily on the sleep dimension, and typically have not incorporated social and environmental influences on chronotype. We propose a multidimensional model of chronotype, integrating individual (biological and psychological), environmental and social factors that appear to interact to determine an individual's true chronotype with potential feedback loops between these factors. This model could be beneficial not only from a basic science perspective but also in the context of understanding health and clinical implications of certain chronotypes as well as designing preventive and therapeutic approaches for related illnesses.

The role of circadian typology in the relationship between perfectionism and workaholism

Workaholism is a work-related addiction, and the study of its antecedents has a strong individual and social impact. Several studies reported high trait perfectionism in individuals exhibiting workaholism. Although the relationship between perfectionism and workaholism is quite consistent in the literature, it is not yet clear which biological underlying mechanisms might explain this relationship. From a chronopsychological perspective, it has been widely demonstrated that evening-type individuals are more prone to develop addictive behaviour. In the present study, we investigated, for the first time, the role of circadian typology in the relationship between perfectionistic concerns and workaholism. A group of Italian workers (N = 369; 60.70% females; mean age of 38.60 years) took part in a survey. Participants filled in the Bergen Work Addiction Scale (for workaholism), the Morningness-Eveningness Questionnaire (for circadian typology), and the Short Almost-Perfect Scale (for perfectionism). In addition to age, we controlled for workload using the Job Content Questionnaire. Beyond the confirmation of the relationship between perfectionism and workaholism, we found that in high perfectionistic individuals, evening-types reported higher score in Bergen Work Addiction Scale. Based on these findings, limitations and suggestions for future research are discussed.

Investigation of the relationship between chronotype, learning style and academic achievement of university students during distance education in the pandemic period

The purpose of this study was to investigate the relationship between chronotype, learning style, and academic achievement. The study sample consisted of 1884 volunteer undergraduate students from 58 different universities across Turkey. The data were collected online during distance education because of the Covid-19 pandemic. Turkish version of Morningness-Eveningness Questionnaire (MEQ) and Big16 Learning Modality Inventory were used for data collection. The correlation between chronotype and cumulative grade point average (CGPA) scores was analyzed using Spearman's rho, and differences among the chronotypes were analyzed with Kruskal-Wallis test. Chi-square tests with pairwise z-test were used to analyze the relationships between the participants' learning style preferences and chronotypes. Also, ANCOVA analyses were performed to evaluate the interactions of gender × chronotype and gender × learning style on CGPA scores. The results revealed that participants' preference for visual and auditory styles differed by chronotype. Visual learning style was more dominant among morning (M) types, while auditory style was more dominant among evening (E) types. However, the most preferred learning style was visual, followed by auditory and kinesthetic styles for all chronotypes. No relationship was found between chronotype and academic achievement. The CGPA scores of the participants with kinesthetic learning style were lower than the participants with auditory and visual learning styles. The female participants had higher CGPA score than males. However, the CGPA scores did not differ for both male and female participants with different chronotype and learning style preferences. From the results, we suggest that academic achievement can be enhanced by consideration of students' learning style preferences for all chronotypes.

Mental health indices may fully mediate the relationship between morningness-eveningness and disease control among adult asthma patients

Objective: The aim of this study was to assess the association between morningness-eveningness and disease control with consideration of mental state as a mediator and the control of confounding factors among adult asthma patients.Methods: This is a cross-sectional study, which included a nonrandom sample of N = 66 patients from an outpatient unit with a confirmed asthma diagnosis, who gave an informed consent and completed a set of questionnaires: a survey comprising questions about sociodemographic and clinical characteristics, the Asthma Control Test (ACT), the Composite Scale of Morningness (CSM), and the General Health Questionnaire (GHQ-28). Mediation models were created separately for each GHQ-28 dimension (somatic symptoms, anxiety/insomnia, social dysfunction and depressive symptoms), for a total score and for four GHQ-28 dimensions together, considered as mediators.Results: Low morning affect was related to poor disease symptom control among patients with asthma. The effect was fully mediated by non-psychotic mental health indices. Evening-time preference was associated with a rise in asthma control, and mediated by somatic symptoms and anxiety/insomnia, when controlled for morning affect.Conclusions: The current study underlines the significance of assessment of both individual morningness-eveningness preference and mental health in the management of asthma symptoms.

Insomnia symptoms mediate the association between eveningness and suicidal ideation, defeat, entrapment, and psychological distress in students

Chronotype describes a person's general preference for mornings, evenings, or neither. It is typically conceptualized as a continuous unidimensional spectrum from morningness to eveningness. Eveningness is associated with poorer outcomes across a myriad of physical and mental health outcomes. This preference for later sleep and wake times is associated with increased risk of depression, anxiety, and suicidal ideation in both clinical and community samples. However, the mechanisms underlying the negative consequences of this preference for evenings are not fully understood. Previous research has found that sleep disturbances may act as a mediator of this relationship. The present study aimed to explore the associations between chronotype and affective outcomes in a sample of students. Additionally, it aimed to investigate the potential role of insomnia as a mediator within these relationships. Participants (n = 190) completed an anonymous self-report survey of validated measures online which assessed chronotype, insomnia symptoms, and a range of affective outcomes (defeat, entrapment, suicide risk, stress, and depressive and anxious symptomology). Eveningness was associated with more severe or frequent experiences of these outcomes, with participants that demonstrated a preference for eveningness more likely to report poorer affective functioning and increased psychological distress. Mediation analysis found the relationship between chronotype and these outcome measures was completely or partially mediated by insomnia symptom severity measured by the validated Sleep Condition Indicator insomnia scale. Taken together, these findings add further evidence for the negative consequences of increased eveningness. Additionally, our results show that chronotype and sleep disturbances should be considered when assessing mental well-being. Implementing appropriate sleep-related behavior change or schedule alterations can offer a tool for mitigation or prevention of psychological distress in students that report a preference for later sleep and wake times.

A six-factor structure of individual variation in the tendencies to become sleepy and to sleep at different times of the day

A multidimensional approach has been previously applied for modeling and assessment of individual differences in the ability to sleep or to stay awake at certain clock hours. More recently the 19 time-point Visuo-verbal Judgment Task (VJT) has been proposed to predict changes in sleepiness level from the morning hours to the next day afternoon. The dimensionality of the VJT has not been explored so far. We applied a structural model of individual variation in sleep-wake behavior and habits for explaining the pattern of relationship between the VJT's dimensions yielded by rotation of principal components with eigenvalue>1. The responses to 19 items of the VJT, 72 items of 6-scale Sleep Wake Pattern Assessment Questionnaire (SWPAQ) and 60 items of 6-scale Sleep-Wake Adaptability Test (SWAT) were collected from 1037 survey participants. Factor analyses yielded 4 factorial dimensions of morning (08:00-11:00), daytime (12:00-20:00), nighttime (21:00-04:00), and after 24 h sleepiness (06:00-12:00 next day). The model was found to be capable to explain the correlations among 4 constructs of the VJT as well as the correlations among previously developed scales of the SWPAQ and SWAT. The results confirmed the predictive power of the model and its applicability for multidimensional assessments in chronobiological and chronopsychological studies.

Chronobiological traits predict the restrained, uncontrolled, and emotional eating behaviors of female university students

Although significant associations between diurnal preference and restrained eating behaviors were previously reported, such reports are scarce and, in some respects, inconclusive. In this cross-sectional survey of 567 female university students aged between 17 and 23 years, we tried to clarify and extend the previous findings on chronobiological correlates of these behaviors. We administered the three-Factor-Eating-Questionnaire Revised and three questionnaires designed to assess trait-, ability-, and state-like differences in the domain of chronobiology, the Morningness-Eveningness Questionnaire (MEQ), the Sleep-Wake Pattern Assessment Questionnaire, and the Munich ChronoType Questionnaire, respectively. Statistical analyses included factor, correlation, and regression analyses. We found that any of three aspects of unhealthy eating behaviors (i.e., lack of cognitive eating restraint, uncontrolled eating, and emotional eating) was linked to one or more dimensions of individual chronobiological differences. We explained the previously reported inconclusive results by the differential relationship of two subconstructs of diurnal preferences to eating behaviors. For instance, such relationship was found for two (morning and evening) subscales of the MEQ. Cognitive eating restraint and uncontrolled eating were related to the morning subscale, while emotional eating was related to the evening subscale. These associations were supported by the associations revealed for morning vs. evening components of earliness-lateness assessed with two other questionnaires, (e.g., morning lateness and sleep offset vs. evening lateness and sleep onset, respectively). We conclude that unhealthy eating behaviors seem to be linked to unhealthy sleep-wake habits and behaviors and to inabilities to wake or sleep on demand at certain times of the day.

Modified Munich chronotype questionnaire for application to short-interval split sleep of non-shift workers

The Munich Chronotype Questionnaire (MCTQ) has been widely validated among various types of populations. However, determination of chronotype among individuals who have a split sleep pattern with short intervals between the first and second sleep bouts on free days has not yet been reported. This study aimed to validate the MCTQ modified for this purpose by assessing the actual sleep-wake timing against the Morningness-Eveningness Questionnaire (MEQ). The modified calculation for the midpoint of sleep on free days (MSF) of the split sleep pattern considers the second sleep bout as the total sleep duration on free days. We recruited 161 participants (mean age: 38.7 ± 7.8 years; 73% females, 29% with split sleep pattern) were recruited to administer the modified version of the MCTQ and MEQ. All of the MCTQ original parameters: midpoint of sleep on work days (MSW, r = -0.575), midpoint of sleep on free days (MSF, r = -0.568), and midpoint of sleep on free days corrected for sleep debt (MSF_sc,r = -0.566) were significantly correlated with MEQ. The MEQ was further tested against MSF in four conditions of the split sleep pattern. The MSF modified for split sleep within 60 minutes after the first awakening showed highest correlation (r = -0.576) against MEQ score. The results demonstrate the modified version of MCTQ is valid to determine the chronotype in participants who practice consolidated and split sleep patterns.

Differences between male and female university students in sleepiness, weekday sleep loss, and weekend sleep duration

INTRODUCTION

Women and men experience sleep differently and the difference in intrinsic desire for sleep might underlie some of the observed male-female differences. The objective of this cross-sectional questionnaire study of university students was to determine male-female differences in self-reported sleepiness and sleep-wake patterns.

METHODS

Five questionnaires were completed by 1650 students at four Russian universities.

RESULTS

Compared to male students, female students reported a lower subjective sleep quality score, had a higher morning sleepability score and lower nighttime and daytime wakeability scores. They more often reported excessive daytime sleepiness and expected to be sleepier at any time of the day with the largest male-female difference around the times of sleep onset and offset. On free days, they reported a longer sleep duration and an earlier sleep onset. Free-weekday difference was larger for sleep duration and smaller for sleep onset. Such male-female differences showed similarity to the differences observed in university and high school students from different countries around the globe. There was no significant male-female difference in weekly averaged sleep duration, weekday sleep duration, hours slept, midpoint of sleep on free days, free-weekday difference in sleep offset, social jetlag, and morningness-eveningness score. Therefore, when studies rely on these self-reports, the most salient male-female differences might not be immediately evident.

CONCLUSIONS

It seems that the intrinsic desire for longer sleep duration might contribute to a higher susceptibility of female students to weekday sleep loss. Among these students, negative effects of reduced sleep duration might be more common and more detrimental.

Owls and larks do not exist: COVID-19 quarantine sleep habits

Background

The coronavirus pandemic presented a unique opportunity to study the daily temporal patterns and sleep habits of humans. The question to be explored was: Are there discernible differences in sleep between the normal operational environment and the stay-at-home condition?

Methods

This international prospective study analyzed results from the sleep-wake patterns questionnaire, daily logs, and interviews. Surveys were administered to the healthy volunteers (age 15–60 y) with stay-at-home for a month or more, without previous sleep disorders and mood-related complaints; volunteers were not involved in online education/work daily timetable-related activities.

Results

We analyzed 3787 subjects with average stay-at-home of 65 ± 9 days. The most significant changes in sleep occurred during the first ten days when the difference between weekdays and weekends disappeared and changes occurred in napping habits. The majority of the participants (66.8%) shifted toward eveningness when the self-selected sleep was possible and 1869 volunteers appeared to be owls (49.4%), 823 (21.7%) exercised “typical” sleep, 478 (12.6%) were larks, and 617 (16.3%) participants were completely desynchronized to the end of stay-at-home. In addition, 497 participants (13.1%) alternated their sleep habits. The most of the desynchronized participants (n = 414) were older than 50 years (age correlation r = 0.80), and predominantly males (n = 297, r = 0.76).

Conclusion

In self-selected sleep conditions, the timing of sleep and sleep habits significantly differ from those of socially and economically fixed daily routine conditions. The changes in daily temporal patterns of humans during a prolonged stay-at-home situation indicate that human sleep habits may change according to existing living conditions.

Validation of the Portuguese Variant of the Munich Chronotype Questionnaire (MCTQPT)

Introduction

Differences in the manner circadian clocks entrain to the 24-h day are expressions of different chronotypes that can range from extreme early to extreme late, from proverbial larks to owls. The Morningness Eveningness Questionnaire (MEQ) was one of the first to assess daily preference based on subjective self-assessment – a psychological construct. The later developed Munich Chronotype Questionnaire (MCTQ) uses instead the actual sleep timing to assess chronotype. It calculates the mid-sleep point, halfway between onset and offset on work-free days (MSF), which is then corrected for potential oversleep on free days compensating for sleep debt accumulated over the workweek (MSF_sc). MSF_sc is expressed in local time and is thought to be a proxy for “phase of entrainment” of the circadian clock. The MCTQ-derived chronotype is therefore a biological construct. In the present report, we validate the Portuguese variant (MCTQ^PT) of the MCTQ. Portugal is of particular interest, since it is thought to consist of especially late chronotypes.

Methods

We have used three methods to assess the timing of daily behavior, namely, the chronotype (MCTQ), the daily preference (rMEQ), and a simple self-assessment (time-of-day type). A total of 80 healthy adults living in Portugal, with age and sex distributed according to the Portuguese population, were recruited. We analyzed 4 weeks of continuous records of actimetry data to validate the MCTQ^PT and used the rMEQ to compare between a biological chronotype (sleep timing) and a psychological chronotype (daily preference). MCTQ variables were analyzed by descriptive statistics; correspondence between measurements was done by Spearman correlations or cross-tabulation; in a subset of 41 individuals, test–retest reliability was assessed.

Results

MCTQ-derived variables (MSF, MSW, MSF_sc) correlated highly with their counterparts calculated from actimetry (MSW: rho = 0.697; MSF: rho = 0.747; MSF_sc: rho = 0.646; all p < 0.001). The MCTQ assessment of the chronotype showed good test–retest reliability (rho = 0.905; p < 0.001). The rMEQ score correlates with MSF_sc (rho = −0.695; p < 0.001), and the agreement for the self-assessment with the MSF_sc was fair (kw = 0.386; p < 0.001).

Conclusion

The Portuguese variant of the MCTQ revealed to be a reliable questionnaire to assess the chronotype for the Portuguese adult population, as previously reported for other countries.

Circadian disruption: What do we actually mean?

The circadian system regulates physiology and behavior. Acute challenges to the system, such as those experienced when traveling across time zones, will eventually result in re-synchronization to local environmental time cues, but this re-synchronization is oftentimes accompanied by adverse short-term consequences. When such challenges are experienced chronically, adaptation may not be achieved, as for example in the case of rotating night shift workers. The transient and chronic disturbance of the circadian system is most frequently referred to as "circadian disruption", but many other terms have been proposed and used to refer to similar situations. It is now beyond doubt that the circadian system contributes to health and disease, emphasizing the need for clear terminology when describing challenges to the circadian system and their consequences. The goal of this review is to provide an overview of the terms used to describe disruption of the circadian system, discuss proposed quantifications of disruption in experimental and observational settings with a focus on human research, and highlight limitations and challenges of currently available tools. For circadian research to advance as a translational science, clear, operationalizable, and scalable quantifications of circadian disruption are key, as they will enable improved assessment and reproducibility of results, ideally ranging from mechanistic settings, including animal research, to large-scale randomized clinical trials.

The Influence of Meal Frequency and Timing on Health in Humans: The Role of Fasting

The influence of meal frequency and timing on health and disease has been a topic of interest for many years. While epidemiological evidence indicates an association between higher meal frequencies and lower disease risk, experimental trials have shown conflicting results. Furthermore, recent prospective research has demonstrated a significant increase in disease risk with a high meal frequency (≥6 meals/day) as compared to a low meal frequency (1⁻2 meals/day). Apart from meal frequency and timing we also have to consider breakfast consumption and the distribution of daily energy intake, caloric restriction, and night-time eating. A central role in this complex scenario is played by the fasting period length between two meals. The physiological underpinning of these interconnected variables may be through internal circadian clocks, and food consumption that is asynchronous with natural circadian rhythms may exert adverse health effects and increase disease risk. Additionally, alterations in meal frequency and meal timing have the potential to influence energy and macronutrient intake.A regular meal pattern including breakfast consumption, consuming a higher proportion of energy early in the day, reduced meal frequency (i.e., 2⁻3 meals/day), and regular fasting periods may provide physiological benefits such as reduced inflammation, improved circadian rhythmicity, increased autophagy and stress resistance, and modulation of the gut microbiota.

Morningness-Eveningness questionnaire in bipolar disorder

The Morningness-Eveningness Questionnaire (MEQ) is among the most commonly used scales to measure chronotype. We aimed to evaluate psychometric properties and clinical correlates of MEQ in bipolar disorder. Patients with a clinical diagnosis of bipolar disorder (n = 53) answered questionnaires for chronotype (MEQ), mood (Quick Inventory of Depressive Symptoms-16, Altman Self-Rating Mania Scale), insomnia (Athens Insomnia Scale, AIS), and sleepiness (Epworth Sleepiness Scale). Mood was evaluated using Montgomery-Åsberg Depression Rating Scale and Young Mania Rating Scale. The MEQ showed high internal consistency with Cronbach's alpha of .85. Lower MEQ scores (eveningness) correlated with insomnia (AIS) (r = -.34, p = .013). The estimate for eveningness (13/53, 24.5%) in our study was higher than in comparable studies in the general population. Patients on lithium exhibited a higher mean MEQ score (56.0 on lithium vs 46.9 with no lithium, p = .007), whereas this score was lower for patients on an antidepressant (46.0 on antidepressants vs 52.6 with no antidepressants, p = .023). We conclude that the MEQ score is psychometrically reliable. However, future studies should further evaluate the association of medication with chronotype. Validation of categorical cut-offs for MEQ in a larger sample of bipolar patients is needed to increase clinical utility.

Larks, owls, swifts, and woodcocks among fruit flies: differential responses of four heritable chronotypes to long and hot summer days

PURPOSE

Drosophila melanogaster and our own species share (Homo sapiens) the history of relatively rapid out-of-Africa dispersal. In Eurasia, they had faced a novel adaptive problem of adjustment of their circadian rhythmicity and night sleep episode to seasonal variation in day length and air temperature. Both species usually respond to heat and a short duration of night by reduction of the amount of night sleep and prolongation of "siesta". To further explore similarities between the two species in the ways of adjustment of their sleep-wake behavior to extreme environmental factors, this study examined the possibility to distinguish four extreme chronotypes among fruit flies and the possibility of the differential response of such chronotypes to light and heat stressors.

MATERIALS AND METHODS

Circadian rhythms of locomotor activity and sleep-wake pattern were tested in constant darkness, and four strains of fruit flies originating from three wild populations of Africa, Europe, and the USA were selected to represent four distinct chronotypes: "larks" (early morning and evening activity peaks), "owls" (late morning and evening peaks), "swifts" (early morning and late evening peaks), and "woodcocks" (late morning and early evening peaks). The circadian rhythms and sleep efficiency of the selected chronotypes were further tested under such extreme conditions as either long day (LD20:4 at 20°C) or a combination of LD20:4 with hot temperature (29°C).

RESULTS

Despite the identity of such experimental conditions for four chronotypes, their circadian rhythms and sleep timing showed significantly distinct patterns of response to exposure to heat and/or long days. All two-way repeated measures analysis of variances yielded a significant interaction between chronotype and time of the day (P<0.001).

CONCLUSION

An experimental study of heritable chronotypes in the fruit fly can facilitate a search for genetic underpinnings of individual variation in vulnerability to circadian misalignment, maladaptive sleep-wake behavior, and sleep disorders.