Stability of chronotype over a 7-year follow-up period and its association with severity of depressive and anxiety symptoms

Bipolar disorder is characterized by chronotype instability: A longitudinal investigation of circadian typology and mood

BACKGROUND

Chronotype is associated with circadian rhythmicity, a core etiological factor underlying bipolar disorder (BD). Given converging evidence linking late chronotype with poor mental health, the goal of the present study was to examine chronotype (in)stability and its relation to mood symptoms over time.

METHODS

Participants with BD I (n = 271), BD II (n = 88), and healthy controls (n = 217) were included (follow-upM=10 years, Range=5-15) from the Prechter Longitudinal Study. Chronotype category and midpoint of sleep, corrected for weekend sleep-debt (MSFsc), were measured with the Munich Chronotype Questionnaire administered every 12 months alongside clinician-rated mood and medication usage. Self-reported mood was measured bi-monthly. Mixed effects models tested whether mood was associated with (in)stability of chronotype category and MSFsc covarying for age, sex, age, and medication.

RESULTS

Compared to HC, individuals with BD self-reported having a later chronotype that significantly fluctuated over time. Individuals with BDI showed significantly less stability in MSFsc than HC. Anticonvulsant use was associated with more stability in MSFsc whereas antidepressant use was associated with less stability in MSFsc.

CONCLUSIONS

In a large longitudinal cohort, individuals with BD displayed significant instability in circadian typology. Psychopharmacology in BD may have differential impacts on circadian timing that is important to monitor.

The validity and reliability of the Chinese version of the biological rhythms interview of assessment in neuropsychiatry in the community: a large Chinese college student population

Objective

To test the psychometric properties of the Chinese version of the biological rhythms interview of assessment in neuropsychiatry (C-BRIAN) in a group of young adults with and without depressive symptoms.

Methods

Three hundred and seventy-eight university students were recruited as participants. Based on the scores from Center for Epidemiological Survey Depression Scale (CES-D), students were divided into the depressed group and healthy group. Explorative factor analysis was applied to assess the construct validity of the C-BRIAN. The Pittsburgh Sleep Quality Index (PSQI) and CES-D were compared with the C-BRIAN to test the convergent validity. The internal consistency of the C-BRIAN was also examined.

Results

Three factors were extracted (activities, eating patterns, and sleep factors) explaining 63.9% of the total variance. The internal consistencies were very good with a coefficient of 0.94 (overall) and 0.89-0.91 for three factors. The domains of activities, eating patterns, and sleep were moderately correlated with PSQI (r=0.579) and CES-D (r=0.559) (ps<0.01).

Conclusion

Our findings suggest that C-BRIAN has good validity and reliability which can be used to assess the biological rhythm in the young adult population with depressive symptoms. C-BRIAN would be a reliable tool to detect depressive symptoms for timely prevention and intervention in the community.

Prospective study of the association between chronotypes and depressive symptoms in Chinese university students: Moderating effects of PER1 gene DNA methylation

Most studies have shown a link between chronotypes and mental health and have identified evening chronotypes (E-types) as a potential risk for depressive symptoms. However, the mechanisms behind this association remain unknown. Abnormal expression of the PER1 gene was not only associated with circadian rhythm disturbance, but also closely related to mental illness. Therefore, this study aimed to examine the association of chronotype with depressive symptoms, and further explore the moderating effects of the PER1 gene DNA methylation on chronotypes and depressive symptoms in Chinese university students. In a stratified cluster sampling design, chronotype and depressive symptoms were assessed in 1 042 university students from 2 universities in a two-year prospective survey from April 2019 to October 2020. The survey was conducted once every 6 months, corresponding to the time points in April 2019 (T0), October 2019 (T1), April 2020 (T2), and October 2020 (T3). At T0, the Morning and Evening Questionnaire 5 (MEQ-5) was adopted to assess chronotype. At T0-T3, the Patient Health Questionnaire 9 (PHQ-9) was adopted to investigate depressive symptoms. Meanwhile, at T0, participants were subjected to a health check-up trip in the hospital, and blood samples were taken from the students to measure the PER1 gene DNA methylation levels. Binary logistic regression was used to analyze the association of chronotypes with depressive symptoms. The depression/total depression group was coded as 1, while the remaining participants was defined as one group, and was coded as 0. The PROCESS plug-in of SPSS software was used to analyze the moderating effects of PER1 gene DNA methylation on the association of chronotype with depressive symptoms. After adjusting for covariates, the results indicated that T0 E-types were positively correlated with T0-T3 depression/total depression in female university students. Furthermore, the PER1 gene DNA methylation has negative moderating effects between T0 chronotype and T3 depressive symptoms and has a sex difference. This study can provide more favorable scientific value for the prevention and control of depression in university students.

The relationship between chronotype and food addiction: Serial mediation of social jetlag and psychological pain

This study evaluates how food addiction is related to chronotype, social jetlag, and psychological pain. Of the participants (n = 1,035 university students), 16.6% had a morning chronotype, 25.1% had an evening chronotype, and 25.1% were clinically addicted to eating. The mean sleep durations for participants were 7.41 ± 2.18 h and 8.95 ± 3.0 h on weekdays and weekends, respectively. The mean misalignment time for social jetlag was 1.45 ± 1.5 h. Food addiction, psychological pain, and social jetlag levels were high among participants with the evening chronotype. The risk factors for food addiction included being female, having an evening chronotype, and having high body mass index levels and psychological pain. The total indirect effect of psychological pain and social jetlag on the relationship between chronotype and food addiction was 20.6%. However, the social jetlag effect is relatively minor compared to psychological pain. The significant conclusions of this study are as follows. Clinical food addiction is prevalent among students, and a strong direct correlation between chronotype and food addiction was observed. The study emphasizes the importance of being aware of chronotype and mental status in establishing a healthy diet and lifestyle.

Evening Chronotype and Suicide: Exploring Neuroinflammation and Psychopathological Dimensions as Possible Bridging Factors-A Narrative Review

A chronotype is generally defined as the variability of the phase angle of entrainment, while the latter reflects the relationship between the timing of a certain rhythm (e.g., the sleep-wake cycle) and the timing of an external temporal cue. Individuals can be placed on a spectrum from "morning types" (M types) to "evening types" (E types). E-chronotype has been proposed as a transdiagnostic risk factor for psychiatric conditions, and it has been associated with psychopathological dimensions. Eveningness seems to be correlated with both suicidal ideation (SI) and suicidal behavior (SB) through several possible mediating factors. Immunological alterations have also been linked to later chronotypes and SI/SB. This narrative review aims to summarize the evidence supporting the possible association between chronotypes and suicide and the eventual mediating role of neuroinflammation and several psychopathological dimensions. A search of the literature (2003-2023) was conducted using various databases: PUBMED, EMBASE, Scopus, UpToDate, PsycINFO, and Cochrane Library. English-language articles were collected and screened for eligibility. Despite the apparent absence of a direct correlation between E-chronotype and suicidality, E-chronotype promotes a chain of effects that could be involved in an increased risk of SB, in which with neuroinflammation possibly plays an intriguing role and some psychopathological dimensions may stand out.

Chronotype characteristics of professional athletes in China: a comprehensive descriptive study

BACKGROUND

Chronotype has gained recognition as a significant factor in enhancing athletic performance. This study aimed to deepen our understanding of athletes' sleep chronotypes and provide a foundation for developing evidence-based training and competition programs. By comprehensively describing and analyzing the chronotype characteristics of Chinese professional athletes, considering individual and sports factors, sleep quality and habits, and mental energy, this research aimed to contribute valuable insights to the field.

METHODS

A sample of 1069 professional athletes from sports teams in Shanghai completed the Athlete Sleep Screening Questionnaire and the Athlete Mental Energy Scale to assess chronotype, sleep quality, sleep-influencing habits, and mental energy.

RESULTS

Among athletes, sleep typology fell within the intermediate range, slightly leaning toward morningness. Male athletes and those who engaged in static sports displayed a greater propensity for morningness. Age correlated with a preference for eveningness. High-level athletes exhibited a stronger inclination toward eveningness. Sleep quality issues were associated with an inclination toward eveningness. Daily caffeine intake and the habit of using electronic devices before bedtime are also linked to eveningness. Chronotype demonstrated the ability to predict various dimensions of athletes' mental energy. It was the strongest predictor of vigor, but the loadings were smaller than those of sleep quality.

CONCLUSION

Chinese athletes' chronotypes primarily exhibit distinct characteristics related to individual factors such as gender, sports discipline, and ranking, as well as habits like caffeine consumption and electronic device use. Moreover, these sleep patterns demonstrate predictive capabilities across all dimensions of athletes' mental energy. This study sheds light on Chinese athletes' unique sleep chronotype attributes, enriching our understanding of sleep patterns among professional athletes under various systems. These insights offer an initial basis for enhancing the effectiveness of athlete scheduling and training management.

The relations between chronotype, stressful life events, and impulsivity in the Adolescent Brain Cognitive Development (ABCD) study

Circadian rhythm disturbances, especially circadian phase delays are associated with impulsive behaviors and have been implicated in psychiatric disorders. Chronotype is a developmentally regulated proxy measure of circadian phase. Past studies have investigated the relationship between chronotype and trauma and found that trauma is associated with evening chronotypes, suggesting the course of chronotype development may be affected by adverse childhood experiences (ACEs). However, the relationships among chronotype, impulsivity and ACEs have largely been studied in a pairwise manner using small, cross-sectional cohorts. We hypothesized that in a cohort of high-risk youth, childhood trauma would be associated with later chronotype, and later chronotype would be associated with higher rates of impulsivity. We analyzed a cross-sectional sample (n = 966) from Year 2 of adolescents at high risk for psychiatric disorders from the ABCD study who were characterized for chronotype, stressful life events, and impulsivity. We used a hierarchical regression model to examine the relationship between chronotype, stressful life events, and impulsivity using the Munich Chronotype Questionnaire (MCTQ), the Life Events Scale, Urgency, Premeditation, Perseverance and Sensation Seeking (UPPS) Impulsive Behavior scale. We found associations between eveningness, stressful life events, and all dimensions of impulsivity. Increased eveningness was associated with a higher number of stressful life events and increased impulsivity. Understanding the role of stressful life events and impulsivity in those predisposed towards eveningness is useful because it may improve our understanding of the biological mechanisms that contribute to psychiatric disorders, and lead to better prevention and treatment efforts using interventions such as increased lifestyle regularity and daytime light exposure.

Sleeping Difficulties, Sleep Duration, and Risk of Hypertension in Women

BACKGROUND

Rates of poor sleep and hypertension are alarming worldwide. In this study, we investigate the association between sleeping difficulties and sleep duration with hypertension risk in women.

METHODS

Sixty-six thousand one hundred twenty-two participants of the Nurses' Health Study 2, who were free of hypertension at baseline (2001), were followed prospectively for 16 years and incident hypertension assessed every 2 years. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) for hypertension incidence associated with sleeping difficulties and sleep duration.

RESULTS

During follow-up, we documented 25 987 incident cases of hypertension. After controlling for demographic and lifestyle risk factors, compared with women who slept 7 to 8 hours, women with shorter sleep duration had a significantly higher risk of hypertension (≤5 hours: HR, 1.10 [95% CI, 1.05-1.16]; 6 hours: HR, 1.07 [95% CI, 1.03-1.10]), whereas the risk for women with longer sleep duration was not statistically significant (9 hours: HR, 1.03 [95% CI, 0.97-1.10]; >9 hours: HR, 1.08 [95% CI, 0.94-1.23]). Compared with women rarely having difficulty falling or staying asleep, women sometimes or usually having these sleep difficulties had significantly higher risk of developing hypertension (HR, 1.14 [95% CI, 1.11-1.17] and 1.28 [95% CI, 1.22-1.35]; Ptrend<0.001). Early morning awakening was not associated with hypertension risk (Ptrend=0.722). There was no effect modification by night work or chronotype.

CONCLUSIONS

Difficulty falling or staying asleep and short sleep duration were associated with higher risk of hypertension among women in our study. Screening for poor sleep could be useful in identifying people at higher risk for hypertension.

Dynamic modelling of chronotype and hypo/manic and depressive symptoms in young people with emerging mental disorders

There is significant interest in the possible influence of chronotype on clinical states in young people with emerging mental disorders. We apply a dynamic approach (bivariate latent change score modelling) to examine the possible prospective influence of chronotype on depressive and hypo/manic symptoms in a youth cohort with predominantly depressive, bipolar, and psychotic disorders (N = 118; 14-30-years), who completed a baseline and follow-up assessment of these constructs (mean interval = 1.8-years). Our primary hypotheses were that greater baseline eveningness would predict increases in depressive but not hypo/manic symptoms. We found moderate to strong autoregressive effects for chronotype (β = -0.447 to -0.448, p < 0.001), depressive (β = -0.650, p < 0.001) and hypo/manic symptoms (β = -0.819, p < 0.001). Against our predictions, baseline chronotypes did not predict change in depressive (β = -0.016, p = 0.810) or hypo/manic symptoms (β = 0.077, p = 0.104). Similarly, the change in chronotype did not correlate with the change in depressive symptoms (β = -0.096, p = 0.295) nor did the change in chronotype and the change in hypo/manic symptoms (β = -0.166, p = 0.070). These data suggest that chronotypes may have low utility for predicting future hypo/manic and depressive symptoms in the short term, or that more frequent assessments over longer periods are needed to observe these associations. Future studies should test whether other circadian phenotypes (e.g. sleep-wake variability) are better indicators of illness course.

Chrononutrition is associated with melatonin and cortisol rhythm during pregnancy: Findings from MY-CARE cohort study

Chrononutrition has been suggested to have an entrainment effect on circadian rhythm which is crucial for metabolic health. Investigating how chrononutrition affects maternal circadian rhythm can shed light on its role during pregnancy. This study aims to determine chrononutrition characteristics of healthy primigravida during pregnancy and its association with melatonin and cortisol rhythm across gestation. A total of 70 healthy primigravidas were recruited from ten randomly selected government maternal and child clinics in Kuala Lumpur, Malaysia. During the second and third trimesters, chrononutrition characteristics including meal timing, frequency, eating window, breakfast skipping, and late-night eating were determined using a 3-day food record. Pregnant women provided salivary samples at five time-points over a 24 h period for melatonin and cortisol assay. Consistently across the second and third trimesters, both melatonin and cortisol showed a rhythmic change over the day. Melatonin levels displayed an increment toward the night whilst cortisol levels declined over the day. Majority observed a shorter eating window (≤12 h) during the second and third trimesters (66 and 55%, respectively). Results showed 23 and 28% skipped breakfast whereas 45 and 37% ate within 2 h pre-bedtime. During the third trimester, a longer eating window was associated with lower melatonin mean (β = -0.40, p = 0.006), peak (β = -0.42, p = 0.006), and AUC_G (β = -0.44, p = 0.003). During both trimesters, a lower awakening cortisol level was observed in pregnant women who skipped breakfast (β = -0.33, p = 0.029; β = -0.29, p = 0.044). Only during the second trimester, breakfast-skipping was significantly associated with a greater cortisol amplitude (β = 0.43, p = 0.003). Findings suggest that certain chrononutrition components, particularly eating window and breakfast skipping have a significant influence on maternal melatonin and cortisol rhythm. Dietary intervention targeting these characteristics may be useful in maintaining maternal circadian rhythm.

Child Eveningness as a Predictor of Parental Sleep

Child eveningness has been associated with many adverse outcomes for children. The aim of this study was to assess whether child eveningness poses a risk to parental sleep quality in follow-up. A total of 146 children (57% adopted, 47% boys, mean age at follow-up 5.1 years [standard deviation 1.7]) completed a 1-week actigraph recording to analyze their sleep twice, 1 year apart. The parents completed the Child ChronoType Questionnaire for their child and a short version of the Morningness-Eveningness Questionnaire for themselves and the Jenkins Sleep Scale for their sleep quality. Linear regression analyses showed that subjective parental sleeping problems at baseline were associated with subjective parental sleeping problems at follow-up. A morning-type child decreased the risk of parental sleeping problems at the 1-year follow-up compared to the child evening chronotype. Additionally, the child intermediate chronotype decreased the risk of maternal sleeping problems at the 1-year follow-up compared to the evening chronotype of the child. Parents of evening-type children experienced more sleeping problems in the follow-up, compared to parents of morning-type children. This finding encourages parents and professionals to steer the diurnal rhythm of evening-type children toward an earlier daily routine.

Insomnia symptoms do, but chronotype does not show relevant associations with mental well-being and negative dream experiences

Chronotypes are diversely associated with sleep quality and mental health. Eveningness is generally associated with lower sleep quality and with increased risk for mental health complaints. Along with insomnia symptoms, frequent dysphoric dreams might be key elements of disturbed sleep, and may also indicate psychological imbalance. Our cross-sectional online study aimed to examine whether eveningness can be considered as an independent risk factor of poor mental well-being or whether this association is explained by symptoms of insomnia. Secondly, we examined the associations between eveningness and frequent dysphoric dreaming taking into account the influence of mental well-being and insomnia complaints. Method: We released an online survey with Morningness-Eveningness Questionnaire, Athens Insomnia Scale, General Mental Health, and frequency of dysphoric dreaming: nightmares and bad dreams separately. We analyzed the data of 2077 participants (MAGE = 28.5, SD = 9.6). Eveningness showed a weak but independent association with mental well-being. Additional analyses showed no signs of associations between eveningness and dysphoric dreaming, such as nightmares and bad dreams. The frequency of bad dreams was associated with insomnia complaints and mental well-being, but nightmare frequency was only linked to insomnia symptoms, but not to mental well-being. Insomnia complaints emerged as a more robust factor in poorer mental well-being than the eveningness preference. Eveningness was not associated with dysphoric dreaming. Restoring insomnia might be essential in individuals at risk for mental health complaints.

Longitudinal associations between high school sleep characteristics and young adult health outcomes

STUDY OBJECTIVES

Short sleep duration and evening chronotype are independently associated with negative health outcomes. However, it is unclear how adolescent sleep duration and chronotype are longitudinally associated with health outcomes during early adulthood.

METHODS

Participants from the NEXT Generation Health Study (n = 2,783; 54.5% female) completed measures of sleep duration (scheduled day and unscheduled day) and chronotype in high school. Sleep duration, chronotype, general health, depressive symptoms, and psychosomatic symptoms were also assessed 4 years after high school. Latent variables estimated high school scheduled-day sleep duration, unscheduled-day sleep duration, and chronotype using the during high school measures. Two path analyses tested the prospective associations between high school sleep duration (separate models for scheduled and unscheduled days) and chronotype with 4 years after high school health outcomes as mediated by concurrent sleep duration and chronotype.

RESULTS

In the scheduled-day model, longer high school sleep duration and later chronotype were associated with longer duration and later chronotype in early adulthood. Longer high school sleep duration was directly associated with fewer psychosomatic symptoms and indirectly associated with fewer depressive and psychosomatic symptoms through longer sleep duration in early adulthood. Later chronotype in high school was indirectly associated with poorer general health, greater depressive symptoms, and greater psychosomatic symptoms in early adulthood through later chronotype.

CONCLUSIONS

Findings highlight the roles of scheduled-day sleep duration and evening chronotype in shaping health outcomes and suggest the importance of chronotype and optimal sleep habits among adolescents.

CITATION

Maultsby KD, Temmen CD, Lewin D, et al. Longitudinal associations between high school sleep characteristics and young adult health outcomes. J Clin Sleep Med. 2022;18(11):2527-2536.

Chronotype, circadian rhythm, and psychiatric disorders: Recent evidence and potential mechanisms

The circadian rhythm is crucial for physiological and behavioral functions. Chronotype, which represents individual preferences for activity and performance, is associated with human health issues, particularly psychiatric disorders. This narrative review, which focuses on the relationship between chronotype and mental disorders, provides an insight into the potential mechanism. Recent evidence indicates that (1) the evening chronotype is a risk factor for depressive disorders and substance use disorders, whereas the morning chronotype is a protective factor. (2) Evening chronotype individuals with bipolar disorder tend to have more severe symptoms and comorbidities. (3) The evening chronotype is only related to anxiety symptoms. (4) The relationship between chronotype and schizophrenia remains unclear, despite increasing evidence on their link. (5) The evening chronotype is significantly associated with eating disorders, with the majority of studies have focused on binge eating disorders. Furthermore, the underlying mechanisms or influence factors are described in detail, including clock genes, brain characteristics, neuroendocrinology, the light/dark cycle, social factors, psychological factors, and sleep disorders. These findings provide the latest evidence on chronotypes and psychiatric disorders and serve as a valuable reference for researchers.

Correlation of Chronotype (Lark versus Night Owl Status) with Mind-Set and Effect of Chronotype on Examination Performance in Veterinary School

Chronotype describes what time of day people are most productive, with the specific terminology of larks (productive early in the day) and night owls (productive late in the day). Society, including education, schedules work at times that generally favor larks. The goals of this study were to (a) define our student population regarding mind-set and chronotype, (b) examine the relationship between chronotype and mind-set score, and (c) examine the relationship between lark score and examination score with examinations offered at varying times of day. The null hypotheses were that there would be no relationships between these variables. If the hypotheses were not proven, this information would be used to educate students about personal management to optimize academic success and to help the college determine if scheduling or other variations in examination implementation could be altered to permit students to demonstrate best their knowledge and skills. There were 184 participants from the classes of 2020-2022. Overall, there were few definite night owls or larks, with 55% of participants categorized as neither. Overall, 78% of students had either a strong growth mind-set or a growth mind-set with some fixed ideas. No meaningful association between chronotype and mind-set score was observed. There was neither a significant main effect for chronotype nor a significant interaction with start time for examinations. Scheduling of examinations in the early morning did not negatively impact student performance based on chronotype in this study.

The moderating role of personality traits in the associations between seasonal fluctuations in chronotype and depressive symptoms

Recent research provided evidence that the well-established association between morningness-eveningness and depressive symptoms may be moderated by personality features - conscientiousness and neuroticism. In the present study, we attempted to broaden these findings using a longitudinal design. We hypothesized that these personality traits may influence the degree to which morningness-eveningness and depressiveness covary in time. Participants (n = 380) filled measures of morningness-eveningness, the Big Five personality, and depressive symptoms twice, in December and in June. Consistent with previous results, we observed a significant seasonal shift towards morningness and lower depressive symptoms from December to June. Seasonal shifts in chronotype and depressive symptoms were interrelated: a seasonal shift towards morningness was associated with a decrease in depressive symptoms. The strength of this association was exaggerated by neuroticism but attenuated by conscientiousness, suggesting that among neurotic individuals seasonal changes in depressive symptomatology are more dependent on seasonal shifts in morningness-eveningness but less dependent among conscientious ones. This result suggests that conscientiousness and emotional stability play a protective role against maladaptive consequences of eveningness.

Predictability of Seasonal Mood Fluctuations Based on Self-Report Questionnaires and EEG Biomarkers in a Non-clinical Sample

Induced by decreasing light, people affected by seasonal mood fluctuations may suffer from low energy, have low interest in activities, experience changes in weight, insomnia, difficulties in concentration, depression, and suicidal thoughts. Few studies have been conducted in search for biological predictors of seasonal mood fluctuations in the brain, such as EEG oscillations. A sample of 64 participants was examined with questionnaires and electroencephalography in summer. In winter, a follow-up survey was recorded and participants were grouped into those with at least mild (N = 18) and at least moderate (N = 11) mood decline and those without self-reported depressive symptoms both in summer and in winter (N = 46). A support vector machine was trained to predict mood decline by either EEG biomarkers alone, questionnaire data from baseline alone, or a combination of the two. Leave-one-out-cross validation with lasso regularization was used with logistic regression to fit a model. The accuracy for classification for at least mild/moderate mood decline was 77/82% for questionnaire data, 72/82% for EEG alone, and 81/86% for EEG combined with questionnaire data. Self-report data was more conclusive than EEG biomarkers recorded in summer for prediction of worsening of depressive symptoms in winter but it is advantageous to combine EEG with psychological assessment to boost predictive performance.

Chronotype changes with age; seven-year follow-up from the Netherlands study of depression and anxiety cohort

BACKGROUND

Chronotype reflects an individual's optimal daily timing of sleep, activity, and cognitive performance. Previous, cross-sectional, studies have suggested an age effect on chronotype with later chronotypes in adolescents and earlier chronotypes in children and elderly. Additionally, later chronotypes have been associated with more depressive symptoms. Few studies have been able to study longitudinal associations between chronotype and age, while adjusting for depressive symptoms.

METHODS

Chronotype was assessed twice with the Munich Chronotype Questionnaire 7 years apart in the Netherlands Study of Depression and Anxiety (T1: N = 1842, mean age (SD): 42.63 years (12.66)) and T2: N = 1829, mean age (SD) 50.67 (13.11)). The longitudinal association between change in age and change in chronotype was tested using a generalized estimated equation analysis adjusted for covariates (including level of depressive symptoms). Using age-bins of 5 years (age at T2), change in chronotype between T1 and T2 was analyzed with Linear Mixed Models.

RESULTS

We found a change towards an earlier chronotype with higher age (B (95% CI): -0.011 (-0.014-0.008), p < 0.001). For the age-bins, the difference in chronotype was significant for the 25-29 years age-bin.

LIMITATIONS

The sample did not include individuals younger than 19 years or older than 68 years.

CONCLUSIONS

In the whole sample chronotype changed towards becoming more morning-type over a period of 7 years, but this change was only significant for those aged 25-29 years. The study was performed in a large naturalistic cohort study with a wide age-range, including patients with a diagnosis of depressive and anxiety disorder and healthy controls.

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.

Sleep-Wake Timings in Adolescence: Chronotype Development and Associations with Adjustment

Adolescent sleep research has focused heavily on duration and quality with less work examining chronotype, defined as individual differences in sleep-wake timings driven by the circadian rhythm. This study filled a gap in the literature by utilizing actigraphy-based sleep estimates in an accelerated longitudinal design in order to better understand the developmental trajectory and individual stability of chronotype during adolescence, as well as the associations between chronotype with risky behaviors, substance use, and depressive symptoms. A total of 329 adolescents (57% female; 21% Asian American, 31% European American, 41% Latino, 7% other ethnicity) provided actigraphy-based estimates of sleep and completed questionnaires at up to three time points, two years apart, beginning at 14-17 years of age. Multilevel modeling revealed a non-linear developmental trend in chronotype whereby eveningness increased from 14 to 19 years of age followed by a trend toward morningness. Individual differences in chronotype exhibited modest stability during adolescent development. Furthermore, greater evening chronotype was associated with more risky behaviors and substance use among males, and more substance use among older adolescents, whereas depressive symptoms were not associated with chronotype. The findings from this study may have practical implications for adolescent behavioral health interventions targeted at reducing risky behaviors and substance use among youth.

Morning affect, eveningness, and amplitude of diurnal variation: associations with parent adult-child relationships, and adult attachment style

Eveningness, as opposed to other chronotypes, in childhood and adolescence is associated with more parental conflicts, such as regarding bed and rising times, which might adversely influence future relationships with parents, and adult attachments. The current survey of 524 Chinese university students (mean = 20.05 and range 18-36 years of age) investigated whether eveningness shows these adverse associations. Morning affect and amplitude distinctness facets of circadian functioning were also assessed. It was found that eveningness is not related to adults' perception of current parental relationships, or to adult attachment security, but low morning affect and stronger amplitude distinctness were associated with perception of more fatherly control, less regard for parents, and more attachment insecurity, and these were related to poorer wellbeing. These findings indicate that components of circadian functioning are related to the quality of adult relationships. Further research is needed to confirm these findings and establish explanatory mechanisms for these associations.

Circadian Functioning and Quality of Life in Substance Use Disorder Patients With and Without Comorbid Major Depressive Disorder

Aim: Although a relationship between circadian disruption and development of several psychiatric disorders, such as major depressive disorder (MDD) and substance use disorder (SUD), has been observed, knowledge on this area is scarce yet. Therefore, this study aims to analyze the circadian functioning and quality of life (QOL) in SUD patients with and without comorbid MDD, two highly prevalent clinical entities with difficult therapeutic management. Methods: One hundred sixty-three male patients under treatment, 81 with SUD and 82 with SUD comorbid major depressive disorder (SUD + MDD), were evaluated. For the circadian functioning assessment, we calculated Social Jet Lag (SJL) and used the reduced Morningness-Eveningness Questionnaire (rMEQ) and the Pittsburgh Sleep Quality Index (PSQI). QOL was measured using the shortened version of the World Health Organization's Quality of Life Questionnaire (WHOQOL-BREF). We collected sociodemographic and clinical variables to evaluate their possible influence on the circadian functioning. Intergroup differences among the variables were examined by different analyses of covariance (ANCOVA and MANCOVA). The possible relationships of quantitative clinical variables with rMEQ, PSQI, and WHOQOL-BREF were explored using bivariate correlation analysis. Results: Lower SJL appears in the SUD + MDD group compared with SUD. The intermediate-type was more prevalent in the SUD group, while a higher percentage of morning-type patients was found in the SUD + MDD. Sleep quality (including latency and daytime dysfunction) was worse for SUD + MDD patients than for SUD even after controlling age and age of SUD onset variables. Last, QOL was poorer in patients with SUD + MDD and, for them, psychological health had a negative relationship with SJL and severity of depression. Conclusions: Our data support and extend previous findings indicating that SUD + MDD is associated with worse clinical characteristics, more sleep problems, and poorer QOL than SUD patients. These results underline the importance of a precise assessment of these measurements in future studies conducted in SUD patients with/without MDD comorbidity that could be considered from a therapeutic point of view.

The effect of subjective sleep latency on BMI of medical interns during and before COVID-19 pandemic

OBJECTIVES

Longer subjective sleep latency and eveningness chronotype are associated with higher BMI. Moreover, COVID-19 lockdown changes have been associated with increased BMI. The aim of this study was to investigate the effect of subjective sleep parameters on BMI of medical interns during and before COVID-19 pandemic.

MATERIAL AND METHODS

This cross-sectional study was performed among medical interns. Bedtime, sleep latency, waking time, sleep duration, and reduced morningness-eveningness scores were evaluated.

RESULTS

There was significant difference between bedtime before (00:11±50) and during (01:10±85) the pandemic in females (p<0.001). The mean circadian score before and during the pandemic showed significant decrease in females (p=0.011). The correlation between BMI with subjective sleep latency in females before and during the pandemic ((r=0.439, p=0.017), (r=0.422, p=0.014)) was significant.

CONCLUSION

COVID-19 pandemic was associated with a change toward nocturnal life among female medical interns. Subjective sleep latency was significantly correlated with BMI in females.

Which are the Central Aspects of Infant Sleep? The Dynamics of Sleep Composites across Infancy

Sleep during infancy is important for the well-being of both infant and parent. Therefore, there is large interest in characterizing infant sleep with reliable tools, for example by combining actigraphy with 24-h-diaries. However, it is critical to select the right variables to characterize sleep. In a longitudinal investigation, we collected sleep data of 152 infants at ages 3, 6, and 12 months. Using principal component analysis, we identified five underlying sleep composites from 48 commonly-used sleep variables: Sleep Night, Sleep Day, Sleep Activity, Sleep Timing, and Sleep Variability. These composites accurately reflect known sleep dynamics throughout infancy as Sleep Day (representing naps), Sleep Activity (representing sleep efficiency and consolidation), and Sleep Variability (representing day-to-day stability) decrease across infancy, while Sleep Night (representing nighttime sleep) slightly increases, and Sleep Timing becomes earlier as one ages. We uncover interesting dynamics between the sleep composites and demonstrate that infant sleep is not only highly variable between infants but also dynamic within infants across time. Interestingly, Sleep Day is associated with behavioral development and therefore a potential marker for maturation. We recommend either the use of sleep composites or the core representative variables within each sleep composite for more reliable research.

Timing of Daily Activities over a 24-Hour Period and Affective Status among a National Cohort of Older Dementia Caregivers

Objective: To examine the allocation of daily activities over a 24-hour period in caregivers (CGs) with and without a probable affective disorder. Methods: Participants were 192 older dementia CGs (mean age = 72.9 years, 70% female) who participated in the National Study of Caregiving. Time diary data were used to measure the duration and timing that caregivers were doing hygienic self-care, eating/drinking, household care, physical caregiving, medical caregiving, socializing, and television viewing. Affective status was assessed using the two-item Patient Health Questionnaire and the Generalized Anxiety Disorder screeners. Results: CGs were more likely to screen positive for depression/anxiety symptoms if they started hygienic self-care later (OR = 1.76, 95% CI = 1.10-2.83) and started medical caregiving later (OR = 2.34, 95% CI = 1.24-4.41). Hygienic self-care start times attenuated the effects of medical caregiving on the affective status. Discussion: Later timing of hygienic self-care may be an important behavioral response that contributes to affective disorder risk in dementia CGs.

Stability of chronotype over a 7-year follow-up period and its association with severity of depressive and anxiety symptoms

BACKGROUND

Chronotype is an individual's preferred timing of sleep and activity, and is often referred to as a later chronotype (or evening-type) or an earlier chronotype (or morning-type). Having an evening chronotype is associated with more severe depressive and anxiety symptoms. Based on these findings it is has been suggested that chronotype is a stable construct associated with vulnerability to develop depressive or anxiety disorders. To examine this, we test the stability of chronotype over 7 years, and its longitudinal association with the change in severity of depressive and anxiety symptoms.

METHODS

Data of 1,417 participants with a depressive and/or anxiety disorder diagnosis and healthy controls assessed at the 2 and 9-year follow-up waves of the Netherlands Study of depression and anxiety were used. Chronotype was assessed with the Munich chronotype questionnaire. Severity of depressive and anxiety symptoms were assessed with the inventory of depressive symptomatology and Beck anxiety inventory.

RESULTS

Chronotype was found to be moderately stable (r = 0.53) and on average advanced (i.e., became earlier) with 10.8 min over 7 years (p < .001). Controlling for possible confounders, a decrease in severity of depressive symptoms was associated with an advance in chronotype (B = 0.008, p = .003). A change in severity of anxiety symptoms was not associated with a change in chronotype.

CONCLUSION

Chronotype was found to be a stable, trait-like construct with only a minor level advance over a period of 7 years. The change in chronotype was associated with a change in severity of depressive, but not anxiety, symptoms.