Circadian typology: a comprehensive review

Cross-cultural validity of Morningness-Eveningness Stability Scale improved (MESSi) in Iran, Spain and Germany

Morningness-Eveningness Stability Scale improved (MESSi) is a newly constructed measure to assess circadian types and amplitude. In this study, we applied this measure to participants from three different countries: Germany, Spain and Iran. Confirmatory factorial analysis (CFA) of MESSi displayed mediocre fit in the three countries. Comparing increasingly stringent models using multigroup confirmatory factor analyses indicated at least partial measurement invariance (metric invariance) by country for Morning Affect and Distinctness subscales. Age was positively related to Morning Affect (MA), and negatively related to Eveningness (EV) and Distinctness (DI). Men reported higher MA than women, whereas women reported higher DI than men. Regarding country effect, Iranian participants reported highest MA compared to Spaniards and Germans, whereas Germans reported higher DI compared to Iranians and Spaniards. As a conclusion, our study corroborated the validity and reliability of MESSi across three different countries with different geographical and cultural characteristics.

Latitude affects Morningness-Eveningness: evidence for the environment hypothesis based on a systematic review

Morningness-eveningness (M/E) is an individual trait related to a person’s sleep-wake cycle and preference for morning or evening hours. The “environment hypothesis” suggests that M/E is dependent on environmental factors, such as latitude, mean average temperature and photoperiod. We here analyzed a large number of datasets to assess this effect based on a systematic review. Data were from a total of 87 datasets and 35,589 individuals based on 28 countries. Partial correlations correcting for age revealed significant relationships between M/E and latitude, mean yearly temperature, photoperiod and sunset. Evening orientation was related to higher latitude, longer days and later sunset. Morning orientation was related to higher average temperatures. Percentage of females and sunrise time had no significant influence. These variables (sunset, temperature, photoperiod) were then input in a general linear model. The full model showed an influence of age and of sunset on CSM scores, but not of photoperiod and average temperature. Sunset, therefore, seems to be the most important statistical predictor for the observed latitudinal gradient.

The Chronotype of Elite Athletes

The aims of this study were (i) to compare the chronotype distribution of elite athletes to a young adult population and (ii) to determine if there was a tendency for athletes to select and/or participate in sports which suited their chronotype. A total of 114 elite athletes from five sports (cricket, cycling, hockey, soccer and triathlon) participated in this study. The participants' chronotype, sleepiness, sleep satisfaction and sleep quality were determined using the Horne and Östberg Morningness and Eveningness questionnaire, the Epworth Sleepiness Scale and questions concerning their sleep satisfaction and quality. All questionnaires were administered during a typical training phase that was not in the lead up to competition and/or post competition. No differences between chronotype group for sleepiness, sleep satisfaction or sleep quality were found. There was a significantly higher proportion of triathletes that were morning and intermediate types compared to the control group χ² (2) = 7.5, p = 0.02. A significant relationship between sport and chronotype group (χ²(4)=15.9, p = 0.04) was observed, with a higher frequency of morning types involved in sports that required morning training. There was a clear indication that athletes tended to select and pursue sports that suited their chronotype. This was evident by the amount of morning types involved in morning sports. Given that athletes are more likely to pursue and excel in sports which suit their chronotype, it is recommended that coaches consider the athlete's chronotype during selection processes or if possible design and implement changes to training schedules to either suit the athletes' chronotype or the timing of an upcoming competition.

Self-Regulation and Sleep Duration, Sleepiness, and Chronotype in Adolescents

OBJECTIVE

To determine whether shorter school-night sleep duration, greater daytime sleepiness, and greater eveningness chronotype were associated with lower self-regulation among adolescents.

METHODS

An online survey of 7th- to 12th-grade students in 19 schools in Fairfax County, Virginia Public Schools was conducted in 2015. Self-regulation was measured with the Behavior Rating Inventory of Executive Function, 2nd edition, Screening Self-Report Form. Sleep measures included school night-sleep duration (hours between usual bedtime and wake time), daytime sleepiness (Sleepiness Scale in the Sleep Habits Survey, tertiles), and chronotype (Morningness-Eveningness Scale for Children, continuous score and tertiles). Sociodemographic factors and mental health conditions were analyzed as potential confounders.

RESULTS

Among 2017 students surveyed, the mean age was 15.0 years (range, 12.1-18.9 years), and 21.7% slept <7 hours on school nights. In regression models adjusted for confounders, there was a significant independent association between self-regulation and both chronotype (P < .001) and daytime sleepiness (P < .001) but not sleep duration (P = .80). Compared with those in the lowest tertile of daytime sleepiness, those in the highest tertile had lower (0.59 SD units; 95% confidence interval, 0.48-0.71) self-regulation, as did those in the eveningness tertile of chronotype compared with those in the morningness tertile (0.35 SD units lower; 95% confidence interval, 0.24-0.46).

CONCLUSIONS

Among adolescents, greater daytime sleepiness and greater eveningness chronotype were independently associated with lower self-regulation, but shorter sleep duration was not. Aspects of sleep other than school-night sleep duration appear to be more strongly associated with self-regulation.

24-h actigraphic monitoring of motor activity, sleeping and eating behaviors in underweight, normal weight, overweight and obese children

PURPOSE

Within a chronobiological perspective, the present study aimed to describe 24 h of sleep-wake cycle, motor activity, and food intake patterns in different body mass index (BMI) categories of children through 7 days of actigraphic recording.

METHODS

Height and weight were objectively measured for BMI calculation in a sample of 115 Italian primary schoolchildren (10.21 ± 0.48 years, 62.61 % females). According to BMI values, 2.60 % were underweight, 61.70 % were of normal weight, 29.60 % were overweight and 6.10 % were obese. Participants wore a wrist actigraph continuously for 7 days to record motor activity and describe sleep-wake patterns. In addition, participants were requested to push the event-marker button of the actigraph each time they consumed food to describe their circadian eating patterns.

RESULTS

BMI group differences were found for sleep quantity (i.e. midpoint of sleep and amplitude), while sleep quality, 24-h motor activity and food intake patterns were similar between groups. Regression analyses showed that BMI was negatively predicted by sleep duration on schooldays. BMI was also predicted by motor activity and by food intake frequencies recorded at particular times of day during schooldays and at the weekend.

CONCLUSIONS

The circadian perspective seems to provide promising insight into childhood obesity, but this aspect needs to be further explored.

Morningness-eveningness in a large sample of German adolescents and adults

People differ in their sleep-wake behavior. This individual difference is conceptualized in different aspects, such as wake up times, bed times, times of peak performance, as well as in morning affect. A total of 14,987 visitors of an exhibition in the LWL State Museum of Natural History, Münster (Germany), did the survey on chronotype and gave their consent that these data can be used for a scientific study. Age groups were coded into 5-year bins. Mean age (mean ± SD) was 28.2 ± 17.5 years. There were 8075 females (54%) and 6912 males in the sample. The German version of the rMEQ (reduced Morningness-Eveningness-Questionnaire) was used for data collection. The data showed clear age effects. Younger children are more morning oriented and become rapidly evening oriented during puberty, while the more attenuated turn towards morningness occurs from the age of 20 years. Then between the ages 25 to 30 morningness-eveningness remained rather stable. Significant gender differences existed in the reproductive age, i.e., the age groups 20 to 50 (corresponding to the age 16–50 years). In other age groups, no gender differences could be detected. Seasonal effects were also found. Chronotype score was lowest during the summer months (and more evening oriented). Based on the single item analysis of the five questions of the rMEQ, we found age group differences in all items. Gender differences occurred in all items except item 1, which deals with the preferred wake-up time. Men always scored significantly lower (i.e. more evening oriented) than women except in item 2 (tiredness after awakening). Seasonal effects were only significant in item 3, which is related to preferred bed times. People showed a later bed time preference during summer. The classification of chronotypes according to the cut-off scores provided by Adan and Almirall (1991) and by using the 20/80 percentile provided identical cut-off scores (values of 11 and below for evening types and 18 and above for morning types).

Student Bedtimes, Academic Performance, and Health in a Residential High School

Inadequate sleep among adolescents is considered an epidemic in the United States. Late night bedtimes could be an important factor in academic performance and health with consequences continuing throughout adulthood. The purpose of this study was to explore the relationships between late night bedtimes, academic performance (grade point average [GPA]), and utilization of health care (school nurse visits) in a residential high school. The data were collected from archival records for one academic semester. The statistical analysis employed the nonparametric Pearson’s correlation coefficient ( r) with the standard level of significance (α = .05). Positive and inverse linear relationships were found between bedtime and school nurse visits ( p < .00001) and bedtime and GPA ( p = .007). The findings suggest students’ late night bedtimes may be related to increased school nurse visits and lower academic performance. Adolescent late night bedtimes may be an important consideration for academic success and maintaining health in residential high schools.

Eveningness and Its Associated Impairments in Remitted Bipolar Disorder

Sleep-wake and circadian rhythm disturbances are common in remitted bipolar disorder. These disturbances include difficulty initiating and maintaining sleep, daytime sleepiness, sleep irregularity, and a circadian tendency toward eveningness. To date, few studies have examined the impact of eveningness on impairments in remitted bipolar disorder. Ninety-eight adults diagnosed with bipolar disorder I, II, or not otherwise specified were evaluated. Hierarchical linear regression analyses showed that eveningness was associated with greater sleep-wake disturbances, more unhealthy dietary habits, worse quality of life, more impaired interpersonal relationships, and more dysfunctional sleep-related cognitions and behaviors, controlling for age, gender, and years of education. Targeted intervention on dysfunctional sleep-related cognitions and behaviors may reverse eveningness and improve functioning in bipolar disorder.

Estimating individual optimal sleep duration and potential sleep debt

In this study, we hypothesized that dynamics of sleep time obtained over consecutive days of extended sleep in a laboratory reflect an individual's optimal sleep duration (OSD) and that the difference between OSD and habitual sleep duration (HSD) at home represents potential sleep debt (PSD). We found that OSD varies among individuals and PSD showed stronger correlation with subjective/objective sleepiness than actual sleep time, interacting with individual's vulnerability of sleep loss. Furthermore, only 1 h of PSD takes four days to recover to their optimal level. Recovery from PSD was also associated with the improvement in glycometabolism, thyrotropic activity and hypothalamic-pituitary-adrenocortical axis. Additionally, the increase (rebound) in total sleep time from HSD at the first extended sleep would be a simple indicator of PSD. These findings confirmed self-evaluating the degree of sleep debt at home as a useful clinical marker. To establish appropriate sleep habits, it is necessary to evaluate OSD, vulnerability to sleep loss, and sleep homeostasis characteristics on an individual basis.

ADHD, circadian rhythms and seasonality

OBJECTIVE

We evaluated whether the association between Adult Attention-Deficit/Hyperactivity Disorder (ADHD) and Seasonal Affective Disorder (SAD) was mediated by the circadian rhythm.

METHOD

Data of 2239 persons from the Netherlands Study of Depression and Anxiety (NESDA) were used. Two groups were compared: with clinically significant ADHD symptoms (N = 175) and with No ADHD symptoms (N = 2064). Sleep parameters were sleep-onset and offset times, mid sleep and sleep duration from the Munich Chronotype Questionnaire. We identified the prevalence of probable SAD and subsyndromal SAD using the Seasonal Pattern Assessment Questionnaire (SPAQ). Clinically significant ADHD symptoms were identified by using a T score>65 on the Conners Adult ADHD Rating Scale.

RESULTS

The prevalence of probable SAD was estimated at 9.9% in the ADHD group (vs. 3.3% in the No ADHD group) and of probable s-SAD at 12.5% in the ADHD group (vs 4.6% in the No ADHD group). Regression analyses showed consistently significant associations between ADHD symptoms and probable SAD, even after adjustment for current depression and anxiety, age, sex, education, use of antidepressants and benzodiazepines (B = 1.81, p < 0.001). Late self-reported sleep onset was an important mediator in the significant relationship between ADHD symptoms and probable SAD, even after correction for confounders (total model effects: B = 0.14, p ≤ 0.001).

CONCLUSION

Both seasonal and circadian rhythm disturbances are significantly associated with ADHD symptoms. Delayed sleep onset time in ADHD may explain the increase in SAD symptoms. Treating patients with SAD for possible ADHD and delayed sleep onset time may reduce symptom severity in these complex patients.

Association of CLOCK, ARNTL, PER2, and GNB3 polymorphisms with diurnal preference in a Korean population

Polymorphisms in human circadian genes are potential genetic markers that affect diurnal preference in several populations. In this study, we evaluated whether four polymorphisms in circadian genes CLOCK, ARNTL, PER2, and GNB3 were associated with diurnal preference in a Korean population. In all, 499 healthy subjects were genotyped for four functional polymorphisms in CLOCK, ARNTL, PER2, and GNB3. Composite scale of morningness (CSM) was applied to measure phenotype patterns of human diurnal preference. In addition, three subscale scores, i.e. "morningness," "activity planning," and "morning alertness," were extracted from the CSM. No significant associations were observed between CSM scores and CLOCK (rs1801260) genotype or T allele carrier status, CSM scores and ARNTL (rs2278749) C allele carrier status, and CSM scores and GNB3 (rs5443) genotype or C allele carrier status. However, total CSM scores and scores of its subscales were significantly associated with PER2 (rs934945) genotype (p = 0.010, p = 0.018, and p = 0.005 for total, morningness, and activity planning, respectively) and G allele carrier status (p = 0.003, p = 0.005, and p = 0.002 for total, morningness, and activity planning, respectively). The best model result obtained by performing multifactor dimensionality reduction analysis ([Formula: see text]² = 11.2798, p = 0.0008) indicated that interaction among C/T single nucleotide polymorphism (SNP) in ARNTL, C/T SNP in GNB3, and G/A SNP in PER2 synergistically affected the risk associated with diurnal preference toward eveningness. These results suggest that circadian gene PER2 is associated with diurnal preference in healthy Korean population. Although polymorphisms in ARNTL and GNB3 were not significantly associated with diurnal preference, their interactions with the polymorphism in PER2 may synergistically increase the risk of diurnal preference toward eveningness.

Sustained wakefulness and visual attention: moderation by chronotype

Introduction

Attentional networks are sensitive to sleep deprivation and increased time awake. However, existing evidence is inconsistent and may be accounted for by differences in chronotype or time-of-day. We examined the effects of sustained wakefulness over a normal “socially constrained” day (following 18 h of sustained wakefulness), following a night of normal sleep, on visual attention as a function of chronotype.

Methods

Twenty-six good sleepers (mean age 25.58; SD 4.26; 54 % male) completed the Attention Network Test (ANT) at two time points (baseline at 8 am; following 18-h sustained wakefulness at 2 am). The ANT provided mean reaction times (RTs), error rates, and the efficiency of three attentional networks—alerting, orienting, and executive control/conflict. The Morningness–Eveningness Questionnaire measured chronotype.

Results

Mean RTs were longer at time 2 compared to time 1 for those with increasing eveningness; the opposite was true for morningness. However, those with increasing morningness exhibited longer RT and made more errors, on incongruent trials at time 2 relative to those with increasing eveningness. There were no significant main effects of time or chronotype (or interactions) on attentional network scores.

Conclusion

Sustained wakefulness produced differential effects on visual attention as a function of chronotype. Whilst overall our results point to an asynchrony effect, this effect was moderated by flanker type. Participants with increasing eveningness outperformed those with increasing morningness on incongruent trials at time 2. The preservation of executive control in evening-types following sustained wakefulness is likely driven by differences in circadian phase between chronotypes across the day.

Circadian rhythmicity in substance use disorder male patients with and without comorbid depression under ambulatory and therapeutic community treatment

Although there have been described alterations of circadian rhythmicity both in patients with substance use disorder (SUD) and patients with major depressive disorder (MDD), the circadian characteristics of SUD patients with comorbid MDD (SUD-MDD) are unknown. Likewise, the possible influence of the different modalities of treatments (ambulatory or therapeutic community) upon the circadian rhythmicity of SUD patients has not been characterized. Therefore, this study analyzes the circadian rhythmic profiles of SUD and SUD-MDD patients under ambulatory and therapeutic community treatment. The sample was composed of 40 SUD and 40 SUD-MDD men, aged 22-55 yrs, under treatment and with abstinence for at least three months (including each group 20 ambulatory and 20 from therapeutic community). Patients completed a sociodemographic, clinical and sleep-wake schedules interview, the Composite Scale of Morningness, and wore on the wrist an ambulatory device known as iButton® Thermochron DS1921H, which registered their distal skin temperature every two minutes for 48 hours. All the groups showed a tendency to morningness without differences among them in concordance with their sleep-wake schedules. With regard to distal skin temperature circadian rhythm, SUD patients showed higher values than SUD-MDD in amplitude, relative amplitude, percentage rhythm, and first harmonic power, and lower minimum temperature in 10 consecutive hours (p < .043, in all cases). Therapeutic community group values were lower in minimum temperature and higher in amplitude, relative amplitude, and 12 harmonic accumulated power (p < .028, in all cases) as compared to ambulatory ones. Moreover, all groups showed higher Rayleigh vector and rhythm stability as compared to normative population (p < .043, in both cases). The circadian rhythmic differences observed for diagnosis and type of treatment are indicative of a higher circadian rhythmicity robustness in SUD and therapeutic community patients as compared to SUD-MDD and ambulatory ones, respectively. Although drug consumption exerts a negative effect on the circadian rhythmicity, our results (high amplitude and rhythm stability) are indicative of an adequate circadian functioning as well as of an adjustment to the light-dark cycle in both diagnosis and type of treatment which may constitute a marker of the adherence to treatment and recovery status.

Smartphone addiction proneness in relation to sleep and morningness-eveningness in German adolescents

Background Mobile phones are an important part of adolescents' life. In this study, the relationships among smartphone addiction, age, gender, and chronotype of German adolescents were examined. Materials and methods Two studies focused on two different measures of smartphone addiction. The Smartphone Addiction Proneness Scale (SAPS) was applied to 342 younger adolescents (13.39 ± 1.77; 176 boys, 165 girls, and 1 not indicated) in Study 1 and the Smartphone Addiction Scale was applied to 208 older adolescents (17.07 ± 4.28; 146 girls and 62 boys) in Study 2, both samples in southwest Germany. In addition, a demographic questionnaire and the Composite Scale of Morningness (CSM) and sleep measures were implemented. Results The most remarkable result of this study was that morningness-eveningness (as measured by CSM scores) is an important predictor for smartphone addiction; even stronger than sleep duration. Evening oriented adolescents scored higher on both smartphone addiction scales. In addition, gender is an important predictor for smartphone addiction and girls are more prone to become addicted. In addition, while sleep duration on weekdays negatively predicted SAPS, age, sleep duration on weekends, and midpoint of sleep on weekdays and weekends did not predicted smartphone addiction in both scales. The analysis of covariance revealed statistically significant effects of the covariates gender and age in both studies, as well as the main effect of chronotype. According to the t-test results, girls had higher scores than boys in smartphone addiction. Conclusion Evening types and girls are more prone to become smartphone addicted.

Personality profile of binge drinking in university students is modulated by sex. A study using the Alternative Five Factor Model

BACKGROUND

The prevalence of binge drinking (BD), found especially among young people, is increasing worldwide and has become an important social and health concern. We studied, for the first time, the personality profile, using the Alternative Five Factor Model, among university students with BD and healthy controls, taking into account the possible influence of sex.

METHODS

70 participants with BD (30 men) and 70 healthy controls (30 men) were included, selected to control for characteristics that are known to be related to BD (physical and mental disorders, consumption of other drugs, circadian rhythms), completed the Zuckerman-Kuhlman Personality Questionnaire (ZKPQ).

RESULTS

The scores on Neuroticism-Anxiety and Impulsive Sensation-Seeking were higher in the BD group compared to the controls (p<0.001 in both cases). The higher scores in the BD group in Neuroticism-Anxiety are due to higher scores in the women's group (p=0.014), while those in Impulsive Sensation-Seeking are due to higher scores in the men's group (p=0.009), both in the Impulsivity and in the Sensation-Seeking subscales (p<0.045).

CONCLUSIONS

Sex could be a factor that modulates the endophenotype of drug dependence (impulsive and anxious personality) and the prevention and/or treatment programs for BD should include not only the management of the personality risk factors but also different tailored approaches according to sex.

Constraint is associated with earlier circadian phase and morningness: Confirmation of relationships between personality and circadian phase using a constant routine protocol

Associations among personality, diurnal preference, and circadian phase were investigated using a constant routine laboratory protocol. One hundred and sixty-eight healthy participants aged 18-30 years (Women n = 68) completed either a 30- or 50-hour constant routine under dim-light conditions (<3 lux), during which circadian phase was measured from core body temperature and melatonin. Prior to laboratory admission, self-report measures of personality and diurnal preference were also obtained. The personality trait of Constraint correlated positively with morning diurnal preference and earlier circadian phase, with circadian phase partially mediating the relationship between Constraint and diurnal preference. No other personality variables correlated with circadian phase. Sex was an important covariate in several of the relationships investigated due to lower levels of Constraint and later CBT phase amongst men and was thus controlled for in all relevant analyses. Findings from this highly controlled study are consistent with previous field research in suggesting that earlier circadian phase is associated with the personality trait of Constraint.

"It's Always the Judge's Fault": Attention, Emotion Recognition, and Expertise in Rhythmic Gymnastics Assessment

In many sports, such as figure skating or gymnastics, the outcome of a performance does not rely exclusively on objective measurements, but on more subjective cues. Judges need high attentional capacities to process visual information and overcome fatigue. Also their emotion recognition abilities might have an effect in detecting errors and making a more accurate assessment. Moreover, the scoring given by judges could be also influenced by their level of expertise. This study aims to assess how rhythmic gymnastics judges' emotion recognition and attentional abilities influence accuracy of performance assessment. Data will be collected from rhythmic gymnastics judges and coaches at different international levels. This study will employ an online questionnaire consisting on an emotion recognition test and attentional test. Participants' task is to watch a set of videotaped rhythmic gymnastics performances and evaluate them on the artistic and execution components of performance. Their scoring will be compared with the official scores given at the competition the video was taken from to measure the accuracy of the participants' evaluations. The proposed research represents an interdisciplinary approach that integrates cognitive and sport psychology within experimental and applied contexts. The current study advances the theoretical understanding of how emotional and attentional aspects affect the evaluation of sport performance. The results will provide valuable evidence on the direction and strength of the relationship between the above-mentioned factors and the accuracy of sport performance evaluation. Importantly, practical implications might be drawn from this study. Intervention programs directed at improving the accuracy of judges could be created based on the understanding of how emotion recognition and attentional abilities are related to the accuracy of performance assessment.

Mediating pathways and gender differences between shift work and subjective cognitive function

OBJECTIVES

Increased injury risk among shift workers is often attributed to cognitive function deficits that come about as a result of sleep disruptions. However, little is known about the intermediate influences of other factors (eg, work stress, health) which may affect this relationship. In addition, gender differences in these the complex relationships have not been fully explored. The purpose of this study is to (1) identify the extent to which work and non-work factors mediate the relationship between shift work, sleep and subsequent subjective cognitive function; and (2) determine if the mediating pathways differ for men and women.

METHODS

Data from the 2010 National Population Health Survey was used to create a cross-sectional sample of 4255 employed Canadians. Using path modelling, we examined the direct and indirect relationships between shift work, sleep duration, sleep quality and subjective cognitive function. Multigroup analyses tested for significantly different pathways between men and women. Potential confounding effects of age and self-reported health and potential mediating effects of work stress were simultaneously examined.

RESULTS

Work stress and sleep quality significantly mediated the effects of shift work on cognition. Age and health confounded the relationship between sleep quality and subjective cognition. No differences were found between men and women.

CONCLUSIONS

Occupational health and safety programmes are needed to address stress and health factors, in addition to sleep hygiene, to effectively address cognitive function among shift workers.

Eveningness and poor sleep quality independently contribute to self-reported depression severity in psychiatric inpatients with affective disorder

Background Chronotype and insomnia have been related to the development and to an unfavourable course of depression. However, the mutual relationship of both risk factors is as yet unclear, especially in acute, clinically manifest depressive disorders. Aims The present study was carried out to elucidate the separate direct and indirect influence of chronotype and poor sleep quality on depression severity in patients hospitalized for depression. Methods Depression severity (BDI-II), chronotype (Morningness-Eveningness Questionnaire), and subjective sleep quality (Pittsburgh Sleep Quality Index total score) were assessed concurrently in inpatients with a depressive syndrome and insomnia during routine treatment. Correlations, multiple regression and bootstrapping methods for testing mediation models were applied to assess the independent direct and indirect effects of chronotype and sleep quality on depression severity, after adjusting for effects of age and gender. Results Data from 57 consecutively admitted patients (88% with major depression) were analyzed (68% women, mean age 41 ± 13 years). Significant correlations between morningness-eveningness (p <0.05) or sleep quality (p <0.01) and depression severity were found; in a multiple regression model comprising chronotype, sleep quality, age and gender, only chronotype (p <0.05) and sleep disturbances (p <0.01) remained as independent significant concurrent predictors of depression severity (R(2) = 0.184, p <0.01). Two mediation models revealed no significant results. Conclusions Eveningness and poor subjective sleep quality were independently and directly associated with higher depression severity in inpatients with depressive syndromes. Chronotype and sleep quality should be taken into account not only in risk assessment and prevention but also in hospitalized patients to develop and improve treatment options.

Associations of pineal volume, chronotype and symptom severity in adults with attention deficit hyperactivity disorder and healthy controls

The pineal gland, as part of the human epithalamus, is the main production site of peripheral melatonin, which promotes the modulation of sleep patterns, circadian rhythms and circadian preferences (morningness vs. eveningness). The present study analyses the pineal gland volume (PGV) and its association with circadian preferences and symptom severity in adult ADHD patients compared to healthy controls. PGV was determined manually using high-resolution 3T MRI (T1-magnetization prepared rapid gradient echo) in medication free adult ADHD patients (N=74) compared to healthy controls (N=86). Moreover, the Morningness-Eveningness Questionnaire (MEQ), the ADHD Diagnostic Checklist and the Wender-Utah Rating Scale were conducted. PGV differed between both groups (patients: 59.9±33.8mm(3); healthy controls: 71.4±27.2mm(3), P=0.04). In ADHD patients, more eveningness types were revealed (patients: 29%; healthy controls: 17%; P=0.05) and sum scores of the MEQ were lower (patients: 45.8±11.5; healthy controls 67.2±10.1; P<0.001). Multiple regression analyses indicated a positive correlation of PGV and MEQ scores in ADHD (β=0.856, P=0.003) but not in healthy controls (β=0.054, P=0.688). Patients' MEQ scores (β=-0.473, P=0.003) were negatively correlated to ADHD symptoms. The present results suggest a linkage between the PGV and circadian preference in adults with ADHD and an association of the circadian preference to symptom severity. This may facilitate the development of new chronobiological treatment approaches for the add-on treatment in ADHD.

Neurobiological Correlates of Psychological Treatments for Insomnia

Abstract. Sleep disorders and sleep disturbances are considered nowadays a major public health problem. Within sleep problems, insomnia is the most common health complaint. The maintenance of insomnia symptoms may lead to a clinical disorder – Insomnia Disorder (ID). A significant amount of literature has shown the efficacy and effectiveness of psychological treatments for ID. Often, the evaluation of therapeutic processes and outcomes focuses on subjective measures such as sleep diaries. In this work, we review the few published studies that evaluate modifications in neurobiological domain related to evidence-based psychological interventions, namely cognitive-behavioral therapy for insomnia (CBT-I). The search was carried out consulting Scopus, PubMed, and ISI Web of Knowledge databases. Only 12 studies were found. From the reviewed papers it was observed that the results are diverse, perhaps due to significant differences pertaining to the methodologies used. However, one interesting finding emerged: daytime experiments on insomnia comprising mainly cognitive tasks denoted hypofunction in ID patients, whereas nighttime experiments mainly associated with affective/emotional tasks denoted hyperarousal. We suggest that the study of the neural changes prompted by CBT-I is a major topic in the domain of psychotherapy and sleep medicine. Despite the scarce studies on neurobiological mechanisms of CBT-I, the results achieved until now are promising and should be taken into account in the future. Nonetheless, more research on this topic is needed.

Patterns of self-reported depressive symptoms in relation to morningness-eveningness in inpatients with a depressive disorder

The stable and persisting preference for activities in the late evening (i.e. eveningness) is associated with a higher risk for depression, suicidality, and non-remission in major depression. The present study investigated symptom patterns in hospitalized patients with depressive syndromes in relation to morningness-eveningness (chronotypes). Depressive symptoms (Beck Depression Inventory [BDI-II]) and chronotype (German version of the Morningness-Eveningness Questionnaire [D-MEQ]) were assessed after admission and before discharge in inpatients with mainly major depression. Group differences of BDI-II single items and three BDI-II factors (cognitive, affective, somatic) between patients divided at the D-MEQ sample median into "morning preference" (MP) and "evening preference" (EP) were calculated. Data from 64 consecutively admitted patients (31MP/33EP) were analyzed. Both groups (MP/EP) were comparable regarding age, sex, diagnosis, length of stay, and subjective sleep quality, BDI-II scores were significantly higher in EP than in MP at admission. At admission and discharge, cognitive symptoms were significantly more pronounced in EP vs. MP; non-significant differences between EP and MP were found for affective and somatic symptoms. The results underline the importance of the trait-like chronotype for severity and symptomatology in patients with depressive disorders. The patients' chronotype should be taken into account in diagnostics and treatment of depressive disorders.

Morningness-eveningness and depressive symptoms: Test on the components level with CES-D in Polish students

BACKGROUND

The study aimed to elucidate previously observed associations between morningness-eveningness and depressive symptomatology in university students. Relations between components of depressive symptomatology and morningness-eveningness were analysed.

METHODS

Nine hundred and seventy-four university students completed Polish versions of the Centre for Epidemiological Studies - Depression scale (CES-D; Polish translation appended to this paper) and the Composite Scale of Morningness. Principal component analysis (PCA) was used to test the structure of depressive symptoms. Pearson and partial correlations (with age and sex controlled), along with regression analyses with morning affect (MA) and circadian preference as predictors, were used.

RESULTS

PCA revealed three components of depressive symptoms: depressed/somatic affect, positive affect, interpersonal relations. Greater MA was related to less depressive symptoms in three components. Morning circadian preference was related to less depressive symptoms in depressed/somatic and positive affects and unrelated to interpersonal relations. Both morningness-eveningness components exhibited stronger links with depressed/somatic and positive affects than with interpersonal relations. Three CES-D components exhibited stronger links with MA than with circadian preference. In regression analyses only MA was statistically significant for positive affect and better interpersonal relations, whereas more depressed/somatic affect was predicted by lower MA and morning circadian preference (relationship reversed compared to correlations).

LIMITATIONS

Self-report assessment.

CONCLUSIONS

There are three groups of depressive symptoms in Polish university students. Associations of MA with depressed/somatic and positive affects are primarily responsible for the observed links between morningness-eveningness and depressive symptoms in university students. People with evening circadian preference whose MA is not lowered have less depressed/somatic affect.

Schooltime subjective sleepiness and performance in Italian primary school children

Despite its clinical importance, the issue of the diurnal time course of sleepiness and performance in children remains largely unexplored. The objective of this study is to draw a profile of daytime subjective sleepiness and performance, at simple and complex tasks, in a cohort of Italian primary school children.To this aim, a sample of 316 children (age range: 5-11 years; mean 8.2 ± 1.5) was recruited and sub-divided into three groups, according to age: Group 1 (5-7 years; N = 127), Group 2 (8-9 years; N = 108), Group 3 (10-11 years; N = 81). Subjective sleepiness and simple performance were evaluated, respectively, through the Pictorial Sleepiness Scale and the Simple Reaction Time Task. Executive functions were addressed by means of the "Go/No-Go Task." Measurements were made in the children's class three times a day, one day a week over a 3-week period in order to reliably reflect the habitual time course of sleepiness and performance, within the following time intervals: a) 8:30 am-10:30 am; b) 11 am-1 pm; c) 2 pm-4 pm.For the global sample, a significant increase of subjective sleepiness was found at the end of school day (2-4 pm), although at relatively low levels. No significant differences were observed in reaction times across the day, whereas a significant worsening was detected in performance at complex task already since mid-morning. Significant correlations were found between subjective sleepiness and complex performance at all points.Slight age-related differences were found in the time courses of subjective sleepiness: in fact, a significant overday reduction of vigilance levels, from mid-morning onwards, was observed in children aged 5-9 years, but not in the older children (10-11 years). However, the daily time course of both simple and complex performances did not differ among children of the three age groups. Our results show changes in vigilance and cognitive functions across a typical school day in childhood, as well as age-related differences in sleepiness profile, that we suggest to thoroughly consider when conceiving chronopsychological interventions in the school context.

Seasonal variations in mood and behavior associate with common chronic diseases and symptoms in a population-based study

The purpose of this study was to assess how seasonality is associated with some of the most common non-communicable diseases (NCDs) in the general Finnish population. The global seasonality score (GSS) was used to measure the magnitude of seasonality in 4689 participants, in addition to which they reported the extent to which the seasonal variations in mood and behavior were experienced as a problem. Regression models and the odds ratios were adopted to analyze the associations adjusted for a range of covariates. Seventy percent of the participants had seasonal variations in sleep duration, social activity, mood, or energy level, and forty percent those in weight and appetite. Angina pectoris and depression were significantly associated with seasonality throughout the analysis. Hypertension, high cholesterol levels, diabetes, other (than rheumatoid) joint diseases and other (than depressive) psychological illnesses were significantly associated with experiencing a problem due to the seasonal variations, with an increase in the GSS, and with seasonal affective disorder and its subsyndromal form. The co-occurrence of the seasonal variations in mood and behavior with certain common NCDs warrants future research to have insights into the etiology and potentially shared pathways and mechanisms of action.

Is problematic mobile phone use explained by chronotype and personality?

In this study, the relationships among problematic mobile phone use, age, gender, personality and chronotype of Turkish university students were examined. The study included 902 university students (73% female, 27% male) and their participation in the study was anonymous and voluntary. Data were collected from each participant by assessing a demographic questionnaire, Composite Scale of Morningness (CSM) as a measure of chronotype, the Big Five Inventory (BIG-5) for personality assessment and Mobile Phone Problem Usage Scale (MPPUS). The most important result was that CSM scores were the best predictor for problematic mobile phone usage, and as a consequence, evening-oriented university students scored higher on the MPPUS. This result remained, even when compared with the most influential personality predictor, conscientiousness. In addition, while extraversion positively predicted, emotional stable and chronotype negatively predicted problematic mobile phone use. Lastly, age and gender were not predictors of problematic mobile phone use.

Morningness-eveningness and amplitude - development and validation of an improved composite scale to measure circadian preference and stability (MESSi)

Measuring morningness-eveningness is an important aspect of individual differences because it is associated with many aspects of personality and health. The present study outlines recent advancements in the field of measurement and proposes an improved assessment of morningness-eveningness, such as the measurement of circadian amplitude, updating and reflecting new item developments, addressing the clock time based measures, the morning-biased items and the aspect of uni versus multidimensionality. Four studies have been carried out in Germany to present a novel development (with a total sample of N = 1181). In study I, the exploratory factor analysis (EFA) revealed three dimensions, one of morningness, one of eveningness and one of amplitude/stability. Then, items were reduced to present a clearer factor structure by removing ambiguous items. In the second study, a shortened questionnaire was applied, with 15 items (5 per construct), but Confirmatory Factor Analysis (CFA) did not provide acceptable fit indices. Refining items were made in study III, which again showed a clearer factor structure in EFA, and subsequently, in study IV, the refined set of 15 items provided a good fit of a CFA. The final questionnaire was tested for validity by applying clock times, personality questions and alertness ratings. Thus, this newly developed questionnaire contains three distinct dimensions. To reflect the new content, the scale is labelled morningness-eveningness-stability-scale improved (MESSi).

Morningness-Eveningness and Physical Activity in Adolescent Girls: Menarche as a Transition Point

This study identified trajectories of morningness-eveningness (M-E) and physical activity when chronological (i.e., time since birth) versus gynecological (i.e., time since menarche) age is used to indicate maturation. Piecewise models were fit for girls (N = 262, ages 11-19) using chronological or gynecological age as the time metric. Girls stayed up later (i.e., eveningness) as they approach menarche. After menarche no change in M-E was observed. In contrast, no change in M-E was detected with chronological age. No change in physical activity was observed before menarche, and physical activity declined after menarche. With chronological age, physical activity declined as girls got older. Gynecological age may be more appropriate than chronological age as a metric for understanding changes in M-E and physical activity.

Time-of-day effects in implicit racial in-group preferences are likely selection effects, not circadian rhythms

Time-of-day effects in human psychological functioning have been known of since the 1800s. However, outside of research specifically focused on the quantification of circadian rhythms, their study has largely been neglected. Moves toward online data collection now mean that psychological investigations take place around the clock, which affords researchers the ability to easily study time-of-day effects. Recent analyses have shown, for instance, that implicit attitudes have time-of-day effects. The plausibility that these effects indicate circadian rhythms rather than selection effects is considered in the current study. There was little evidence that the time-of-day effects in implicit attitudes shifted appropriately with factors known to influence the time of circadian rhythms. Moreover, even variables that cannot logically show circadian rhythms demonstrated stronger time-of-day effects than did implicit attitudes. Taken together, these results suggest that time-of-day effects in implicit attitudes are more likely to represent processes of selection rather than circadian rhythms, but do not rule out the latter possibility.

Genome-wide association analysis identifies novel loci for chronotype in 100,420 individuals from the UK Biobank

Our sleep timing preference, or chronotype, is a manifestation of our internal biological clock. Variation in chronotype has been linked to sleep disorders, cognitive and physical performance, and chronic disease. Here we perform a genome-wide association study of self-reported chronotype within the UK Biobank cohort (n=100,420). We identify 12 new genetic loci that implicate known components of the circadian clock machinery and point to previously unstudied genetic variants and candidate genes that might modulate core circadian rhythms or light-sensing pathways. Pathway analyses highlight central nervous and ocular systems and fear-response-related processes. Genetic correlation analysis suggests chronotype shares underlying genetic pathways with schizophrenia, educational attainment and possibly BMI. Further, Mendelian randomization suggests that evening chronotype relates to higher educational attainment. These results not only expand our knowledge of the circadian system in humans but also expose the influence of circadian characteristics over human health and life-history variables such as educational attainment.