Biological rhythm differences and suicidal ideation in patients with major depressive disorder

A prospective examination of sleep chronotype and future suicide intent among adults in the United Kingdom: A test of the integrated motivational volitional model of suicide

OBJECTIVES/BACKGROUND

Prior research identified a connection between evening chronotype and suicidality, but the mechanism underlying that connection is not well understood. The Integrated Motivational Volitional (IMV) Model of Suicide may provide a theoretical explanation for this link. The current project includes a three-time point longitudinal survey to examine whether 1) suicide intent likelihood varies across time, 2) chronotype affects suicide intent likelihood prospectively, and 3) defeat and entrapment explain the association between chronotype and suicide intent likelihood.

PATIENTS/METHODS

Participants (n = 187 UK adults) completed a baseline survey (demographics, chronotype (morning-eveningness; MEQ), defeat and entrapment, and perceived intent to make a future suicide attempt), and follow-up surveys (MEQ and suicide intent likelihood) 3 and 6 months later.

RESULTS

Results indicated that suicidal intent at 6-month follow-up was lower than baseline or 3-month follow-up. It was also found that strong evening chronotype at baseline is associated with increased suicidal intent 6 months later, and that defeat mediates this relationship.

CONCLUSION

Our theoretically informed findings shed light on the psychological mechanisms linking chronotype (i.e., eveningness) and future suicide intent by highlighting the role of defeat and entrapment. We propose that feelings of defeat might be derived from evening types' experiences of social jetlag (resulting from conflict between biologically driven sleep schedules and externally dictated social schedules), which consequently drives entrapment and greater future suicide intent. Within this context, defeat and entrapment may be good transdiagnostic and modifiable target variables for future intervention development.

Pre-COVID-19 short sleep duration and eveningness chronotype are associated with incident suicidal ideation during COVID-19 pandemic in medical students: a retrospective cohort study

Introduction

Cross-sectional evidence suggests that sleep problems increased the risk of suicide during the 2019 coronavirus disease (COVID-19) pandemic. However, a lack of longitudinal studies examined the relationship between pre-COVID-19 sleep duration, chronotype and incident suicide during the COVID-19 pandemic. Thus, we examined these associations in a longitudinal study of medical students.

Methods

From the Shantou College Student Sleep Cohort, a total of 333 first and second grade medical students (age 19.41 ± 0.82 years, female 61.26%), without suicidal ideation (SI) at pre-COVID-19 period, were followed up during the COVID-19 pandemic. Incident SI was defined by their response to the 9th question from the Beck Depression Inventory. Short sleep duration was defined as less than 7 h/night. The Morningness-Eveningness Questionnaire was used to evaluate the participants' chronotype. Logistic regression with adjusted odds ratios (AOR) and 95% confidence intervals (95% CI) was used to examine the association between sleep and SI.

Results

The incidence of SI during the COVID-19 pandemic was 5.71%. Logistic regressions with confounding factors adjustment showed that both short sleep duration (AOR = 4.91, 95% CI = 1.16-20.74) and eveningness (AOR = 3.80, 95% CI = 1.08-13.30) in the pre-COVID-19 period were associated with increased risk of incident SI during the COVID-19 pandemic.

Conclusion

Pre-COVID-19 short sleep duration and eveningness predict incident SI during the COVID-19 pandemic in medical students. Prolonging sleep duration may help to decrease SI during major public health crises.

Circadian rhythms and mood disorders: Time to see the light

The importance of time is ever prevalent in our world, and disruptions to the normal light/dark and sleep/wake cycle have now become the norm rather than the exception for a large part of it. All mood disorders, including seasonal affective disorder (SAD), major depressive disorder (MDD), and bipolar disorder (BD), are strongly associated with abnormal sleep and circadian rhythms in a variety of physiological processes. Environmental disruptions to normal sleep/wake patterns, light/dark changes, and seasonal changes can precipitate episodes. Moreover, treatments that target the circadian system have proven to be therapeutic in certain cases. This review will summarize much of our current knowledge of how these disorders associate with specific circadian phenotypes, as well as the neuronal mechanisms that link the circadian clock with mood regulation. We also discuss what has been learned from therapies that target circadian rhythms and how we may use current knowledge to develop more individually designed treatments.

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.

Can morning affect protect us from suicide? The mediating role of general mental health in the relationship between chronotype and suicidal behavior among students

Although chronotype has been associated with suicidal behavior, current research suggest that this relationship may be mediated by other factors. The aim of this study was to assess whether chronotype, specifically morningness, may predict suicidal behavior and whether this relationship may be mediated by general mental health, depressive and anxiety symptoms, and/or social functioning among young adults. The study group comprised 306 students: 204 (65.8%) women, 101 (32.6%) men and one who chose not to identify with either option (0.3%). The participants completed The Composite Scale of Morningness, The General Health Questionnaire, 30-item version, Suicide Acceptance Questionnaire and The Suicidal Behaviors Questionnaire-Revised. Correlations between the continuous variables of interest revealed a weak, but significant, negative association between morning affect (CSM) and suicidal behavior (SBQ-R); a moderate positive association was found between suicidal behavior (SBQ-R) and depression/anxiety, and a weak one between suicidal behavior (SBQ-R) and interpersonal relations (GHQ-30). The models predicting suicidal behavior, and chronotype-related variables as predictors of suicidal behavior, were then tested. Although the morning affect predicted suicidal behavior, this effect became irrelevant when combined with mental health characteristics: psychopathological symptoms of depression and anxiety and the quality of interpersonal relations. Our findings imply that the role of chronotype is secondary to general mental health: mental disorder symptoms should be considered as the core risk factors for suicide and serve as the focus for suicide risk assessments.

Association between mobile phone addiction, chronotype and nonsuicidal self-injury among adolescents: A large-scale study in China

BACKGROUND

Nonsuicidal self-injury (NSSI) is a serious public health and clinical problem, particularly for adolescents, and may link to problematic smartphone use (PSU) and chronotype. This study examines the independent and interaction effects of PSU and chronotype on NSSI among adolescents and identified gender differences in these associations.

METHODS

A total of 21,357 students aged 11-19 were recruited using stratified cluster sampling across five representative provinces in China and completed standard questionnaires to record details of PSU, chronotype, and NSSI.

RESULTS

A total of 38.1 % of students reported having engaged in NSSI and 17.7 % had PSU. PSU and chronotype were significantly associated with NSSI among adolescents, and this relationship was stronger in females. Interaction analysis indicated that E-type and PSU were interactively associated with increased risks of NSSI.

CONCLUSION

The findings suggest that E-type and PSU can increase the risk of NSSI both independently and interactively. Therefore, they should be considered in intervention programs for NSSI, especially for females.

Physical Activity Patterns, Circadian Rhythms, and Aggressive and Suicidal Behavior among a Larger Sample of the General Population Aged 15 to 34 Years

BACKGROUND

From a psychological perspective, aggressive behavior, non-suicidal self-injury and suicidal behavior could be considered dysfunctional coping strategies. Poor sleep patterns may further increase such dysfunctional coping. In contrast, regular physical activity may have the power to counteract such dysfunctional coping. Given this background, the aim of the present study was to combine categories of circadian rhythms as a proxy of normative sleep patterns and categories of physical activity patterns, and to associate these categories with aggressive behavior, non-suicidal self-injury and suicidal behavior among a larger sample of adolescents and young adults, aged 15 to 34 years.

METHOD

A total of 2991 (55.6% females) individuals aged 15 to 34 years of the so-called Ravansar non-communicable disease cohort study (RaNCD) took part in this study. Participants completed self-rating questionnaires covering circadian-related sleep patterns, regular physical activity, socio-demographic information and dimensions of aggression, non-suicidal self-injury and suicidal behavior.

RESULTS

In a first step, both sleep patterns (circadian rhythm disorder: yes vs. no) and physical activity patterns (high vs. low) were dichotomized. Next, participants were assigned to one of four prototypical clusters: No circadian sleep disorders and high physical activity ("Hi-Sleep-Hi-PA"); no circadian sleep disorders and low physical activity ("Hi-Sleep-Lo-PA"); circadian sleep disorders and high physical activity ("Lo-Sleep-Hi-PA"); circadian sleep disorders and low physical activity ("Lo-Sleep-Lo-PA"). Projecting these four clusters on dimensions of aggressive behavior, non-suicidal self-injury and suicidal behavior, the following findings were observed: Participants of the "Hi-Sleep-Hi-PA" reported the lowest scores for aggressive behavior, self-injury and suicidal behavior, compared to participants of the "Lo-Sleep-Lo-PA" cluster. No differences for aggressive behavior, self-injury and suicidal behavior were observed among participants of the "Hi-Sleep-Lo-PA" and the "Lo-Sleep-Hi-PA" clusters.

CONCLUSIONS

It appeared that the combination of favorable circadian sleep patterns and high physical activity patterns was associated with lower aggressive behavior, lower self-injury and suicidal behavior as proxies of favorable psychological functioning. In contrast, persons reporting high circadian sleep disorders and low physical activity patterns appeared to demand particular attention and counseling for both their lifestyle issues (sleep and physical activity) and their dysfunctional coping strategies.

Seasonality of brain function: role in psychiatric disorders

Seasonality patterns are reported in various psychiatric disorders. The current paper summarizes findings on brain adaptations associated with seasonal changes, factors that contribute to individual differences and their implications for psychiatric disorders. Changes in circadian rhythms are likely to prominently mediate these seasonal effects since light strongly entrains the internal clock modifying brain function. Inability of circadian rhythms to accommodate to seasonal changes might increase the risk for mood and behavior problems as well as worse clinical outcomes in psychiatric disorders. Understanding the mechanisms that account for inter-individual variations in seasonality is relevant to the development of individualized prevention and treatment for psychiatric disorders. Despite promising findings, seasonal effects are still understudied and only controlled as a covariate in most brain research. Rigorous neuroimaging studies with thoughtful experimental designs, powered sample sizes and high temporal resolution alongside deep characterization of the environment are needed to better understand the seasonal adaptions of the human brain as a function of age, sex, and geographic latitude and to investigate the mechanisms underlying the alterations in seasonal adaptation in psychiatric disorders.

Reliability and validity of the Chinese version of the biological rhythms interview of assessment in neuropsychiatry in patients with major depressive disorder

BACKGROUND

Although disturbances in biological rhythms are closely related to the onset of major depressive disorder (MDD), they are not commonly assessed in Chinese clinical practice. The Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN) has been used to evaluate disturbances in biological rhythms in MDD. We aimed to assess and confirm the reliability and validity of the Chinese version of the BRIAN (C-BRIAN) in patients with MDD.

METHODS

A total of 120 patients with MDD and 40 age- and sex-matched controls were recruited consecutively. Reliability was estimated using Cronbach's alpha, the split-half coefficient, and the test-retest coefficient; test-retest reliability was assessed using Spearman's correlation coefficient. A confirmatory factor analysis was used to determine the construct validity of the scale. The Pittsburgh Sleep Quality Index (PSQI) and the Morningness-Eveningness Questionnaire (MEQ) were used to check concurrent validity by evaluating the correlation between the C-BRIAN, PSQI, and MEQ.

RESULTS

The overall Cronbach's α value was 0.898, indicating good internal consistency. The Guttman split-half coefficient was 0.792, indicating good split-half reliability. Moreover, the test-retest reliability for both the total and individual item score was excellent. Confirmatory factor analysis revealed that construct validity was acceptable (χ2/df = 2.117, GFI = 0.80, AGFI = 0.87, CFI = 0.848, and RMSEA = 0.097). Furthermore, total BRIAN scores were found to be negatively correlated with MEQ (r = - 0.517, P < 0.001) and positively correlated with PSQI (r = 0.586, P < 0.001). In addition, patients with MDD had higher BRIAN scores than those in controls.

CONCLUSIONS

This study revealed that the C-BRIAN scale has great validity and reliability in evaluating the disturbance of biological rhythms in patients with MDD.

Sleep disturbance and psychiatric disorders: a bidirectional Mendelian randomisation study

AIMS

Sleep disturbance is an important factor in the pathophysiology and progression of psychiatric disorders, but whether it is a cause, or a downstream effect is still not clear.

METHODS

To investigate causal relationships between three sleep-associated traits and seven psychiatric diseases, we used genetic variants related to insomnia, chronotype and sleep duration to perform a two-sample bidirectional Mendelian randomisation analysis. Summary-level data on psychiatric disorders were extracted from the Psychiatric Genomics Consortium. Effect estimates were obtained by using the inverse-variance-weighted (IVW), weights modified IVW, weighted-median methods, MR-Egger regression, MR pleiotropy residual sum and outlier (MR-PRESSO) test and Robust Adjusted Profile Score (RAPS).

RESULTS

The causal odds ratio (OR) estimate of genetically determined insomnia was 1.33 (95% confidence interval (CI) 1.22-1.45; p = 5.03 × 10-11) for attention-deficit/hyperactivity disorder (ADHD), 1.31 (95% CI 1.25-1.37; p = 6.88 × 10-31) for major depressive disorder (MDD) and 1.32 (95% CI 1.23-1.40; p = 1.42 × 10-16) for post-traumatic stress disorder (PTSD). There were suggestive inverse associations of morningness chronotype with risk of MDD and schizophrenia (SCZ). Genetically predicted sleep duration was also nominally associated with the risk of bipolar disorder (BD). Conversely, PTSD and MDD were associated with an increased risk of insomnia (OR = 1.06, 95% CI 1.03-1.10, p = 7.85 × 10-4 for PTSD; OR = 1.37, 95% CI 1.14-1.64; p = 0.001 for MDD). A suggestive inverse association of ADHD and MDD with sleep duration was also observed.

CONCLUSIONS

Our findings provide evidence of potential causal relationships between sleep disturbance and psychiatric disorders. This suggests that abnormal sleep patterns may serve as markers for psychiatric disorders and offer opportunities for prevention and management in psychiatric disorders.

Associations of Childhood Maltreatment With Suicidal Behavior Among Chinese Adolescents: Does It Differ Based on Gender and Biological Rhythm?

BACKGROUND

The impact of biological rhythm disorder (BRD) on the association of childhood maltreatment (CM) and suicidal behavior in adolescents remains unclear. CM increases the risk of suicidal ideation (SI), suicidal planning (SP), and suicidal attempts (SAs). There is less investigation on gender differences in CM's effects on suicidal behavior. It is unknown whether the impacts vary with different levels of BRD.

AIMS

To identify gender differences in CM's effects on suicidal behavior and to investigate these impacts at different levels of BRD.

METHOD

The analysis is based on data from 7,986 adolescents recruited from three cities in China between October and December 2019. All participants, aged 14.7 ± 2 years, filled out standard questionnaires involving CM, BRD, and suicidal behavior.

RESULTS

A total of 22.9, 10.8, and 4.7% of the adolescents reported SI/SP/SAs in the past year. Girls are more likely to engage in SI and SP when exposed to the highest level of CM; boys are more likely to engage in SAs than girls. A significant relationship between moderate levels of CM and SI/SP/SAs was only observed in girls exposed to low BRD. Moderate CM is only significantly associated with SI in boys exposed to low BRD. The percentage of low-BRD adolescents who experienced high CM was 31.4%, whereas 58% of high-BRD adolescents experienced high CM in SI. Adolescents with high BRD were more likely to experience high levels of CM in SP and SAs.

CONCLUSIONS

Adolescents at high risk of suicidal behavior in relation to CM should be targeted accordingly. Improving biological rhythm in adolescents who experience CM could help prevent them from engaging in suicidal behavior.

Development and validation of the self-rating of biological rhythm disorder for Chinese adolescents

Modern lifestyles, and the popularization of artificial light at night, have led to maladjusted social time and internal circadian rhythm, so developing an instrument on biological rhythms is critical. A 36-item self-rated questionnaire assessing biological rhythm disorder in adolescents was developed according to the literature and expert evaluations. Based on a literature review, four dimensions, digital media use, sleep, eating habits, and activity, were determined. After preliminary item analysis, seven unqualified items were eliminated. A total of 1,152 college students and 8,082 middle school students were selected. Two independent sample t-tests, the Pearson correlations, and confirmatory factor analysis, were used to evaluate the reliability and validity of the questionnaire. The final questionnaire consisted of 4 dimensions covering 29 items, and the variance cumulative contribution was 62.65%. Cronbach's α for the total questionnaire was 0.950 and ranged from 0.817 to 0.904 for each dimension. The Pearson correlation coefficients between each item and the total score ranged from 0.360 to 0.755, and the Pearson correlation coefficient between each item and its dimension was between 0.575 and 0.841. Confirmatory factor analysis showed that the indices of CFI, TLI and RMSEA were 0.911, 0.901 and 0.043, respectively, which is a good degree of fit. The self-rating scale is consistent with the evaluation standard of psychometrics and can be used to evaluate the degree of biological rhythm disorder in adolescents.

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.

The effect of age and chronotype on seasonality, sleep problems, and mood

Seasonal affective disorder has been associated with sleep problems, young age, and an evening chronotype. A chronotype refers to an individual's preference in the timing of their sleep-wake cycle, as well as the time during the sleep-wake cycle when a person is most alert and energetic. Seasonality refers to season-dependent fluctuations in sleep length, social activity, mood, weight, appetite, and energy level. Evening chronotype is more common in young adults and morning chronotype more common in the elderly. This study aimed to estimate the differential contribution of chronotype and age on seasonality. A sample of n=410 participants were included in the study. The age groups showed significantly different results according to sleep parameters, depression, anxiety, stress, seasonality, and chronotype. The oldest group (>59 years) showed the lowest scores on all of these scales. According to a path analysis, chronotype and age predict propensity for seasonality. However, sleep problems were linked to chronotype but not to age. Older adults seem to be more resistant to seasonal changes that are perceived as a problem than young and middle aged adults. Future studies would benefit from considering cultural aspects and examine seasonality, chronotype, depression, and insomnia in longitudinal designs.

The association between chronotype and suicidality among students of the medicine and psychology faculties - the mediating role of general mental health indices

The aim of the present study was to evaluate whether anxiety and insomnia symptoms, somatic symptoms, and social dysfunction mediate the link between chronotype and suicidality, as depressive symptoms are known to do, among students of the faculties of Medicine and Psychology. Data from a total of 289 students were eligible for the analysis. The students completed the Suicide Behaviors Questionnaire - Revised, Composite Scale of Morningness, General Health Questionnaire. Single-predictor linear regression models were created to predict suicidality, with a subsequent mediation analysis. A preference toward eveningness was associated with an increase in suicidality Somatic symptoms, anxiety/insomnia, and depressive symptoms fully mediated the relationship between chronotype and suicidality. Depressive symptoms were found to present the strongest effect size of mediation. Social dysfunction was associated with both eveningness and suicidality, but did not play a mediating role. There might be a need to evaluate nonpsychotic mental health indices other than depressive symptoms when assessing the link between suicidality and chronotype among students of the faculties of Medicine and Psychology.

Higher prevalence of intentional self-harm in bipolar disorder with evening chronotype: A finding from the APPLE cohort study

BACKGROUND

Patients with bipolar disorder (BD) frequently self-harm, and this is strongly associated with subsequent suicide. This study investigated the association between chronotype and intentional self-harm in patients with BD.

METHODS

Two-hundred and five outpatients with BD participated in this cross-sectional study. Each participant's chronotype was evaluated using the Morningness-Eveningness Questionnaire, dividing the scores into three types: evening, 16-41 points; intermediate, 42-58 points; and morning, 59-86 points. Intentional self-harm over the past year were self-reported by questionnaire. Propensity score for evening chronotype was estimated from age, sex, socioeconomic factors, mood symptoms, total sleep time, age at the onset of BD, psychiatric inpatient history, family history of suicide, psychiatric comorbidity, and use of lithium.

RESULTS

Thirty-six (18%) of the 205 participants reported self-harm. A substantially higher proportion of the evening chronotype group self-harmed compared to the other groups (evening, 37%; intermediate, 13%; morning 10%). In multivariable analysis adjusted for propensity score, the odds ratio (OR) for self-harming significantly increased from morning to intermediate to evening chronotype (ORs: morning, 1.00; intermediate, 1.56; evening, 3.61; P for trend = 0.038).

LIMITATIONS

This study was a cross-sectional and small sample size.

CONCLUSIONS

Although a third factors, such as personality disorder or disrupted circadian rhythm, may have influenced, these findings suggest association between chronotype and intentional self-harm in BD patients.

Micro RNAs and the biological clock: a target for diseases associated with a loss of circadian regulation

Background

Circadian clocks are self-sustaining oscillators that coordinate behavior and physiology over a 24 hour period, achieving time-dependent homeostasis with the external environment. The molecular clocks driving circadian rhythmic changes are based on intertwined transcriptional/translational feedback loops that combine with a range of environmental and metabolic stimuli to generate daily internal programing. Understanding how biological rhythms are generated throughout the body and the reasons for their dysregulation can provide avenues for temporally directed therapeutics.

Summary

In recent years, microRNAs have been shown to play important roles in the regulation of the circadian clock, particularly in Drosophila, but also in some small animal and human studies. This review will summarize our current understanding of the role of miRNAs during clock regulation, with a particular focus on the control of clock regulated gene expression.

A double-blind, randomized, placebo-controlled trial of adjunctive blue-blocking glasses for the treatment of sleep and circadian rhythm in patients with bipolar disorder

OBJECTIVES

Recent studies have suggested that evening blue light exposure is associated with sleep and circadian rhythm abnormalities. This study examined the effect of blue-blocking (BB) glasses on sleep and circadian rhythm in patients with bipolar disorder (BD).

METHODS

We used a randomized, placebo-controlled, double-blinded design. Outpatients with BD and also with insomnia were randomly assigned to wear either orange glasses (BB) or clear ones (placebo) and were instructed to use these from 20:00 hours until bedtime for 2 weeks. The primary outcome metric was the difference in change from baseline to after intervention in sleep quality, as measured by the visual analog scale (VAS).

RESULTS

Forty-three patients were included in this study (BB group, 21; placebo group, 22). The change in sleep quality as per the VAS metric was not significantly different between the two groups (95% confidence interval [CI], -3.34 to 24.72; P = .13). However, the Morningness-Eveningness Questionnaire score had shifted to an advanced rhythm in the BB group and to a delayed rhythm in the placebo group, and the difference in these changes was statistically significant (95% CI, 1.69-7.45; P = .003). The change in the actigraphy sleep parameters and mood symptoms was not significantly different between the two groups.

CONCLUSION

Although concurrent medications may have influenced, our results suggest that BB glasses may be useful as an adjunctive treatment for circadian rhythm issues in patients with BD.

The clinical problem of the lethality of insomnia: a new empirical exploration from a clinical trial

Moul DE. The clinical problem of the lethality of insomnia: a new empirical exploration from a clinical trial. J Clin Sleep Med. 2020;16(8):1225–1227.

An exploratory analysis of the association of circadian rhythm dysregulation and insomnia with suicidal ideation over the course of treatment in individuals with depression, insomnia, and suicidal ideation

STUDY OBJECTIVES

Sleep disturbance is significantly associated with suicidal ideation. However, the majority of past research has examined the relationship between insomnia and suicidality. The current exploratory study examined the relationship of circadian rhythm dysregulation (eveningness, seasonality, and rhythmicity) with suicidality.

METHODS

We examined the association of insomnia, eveningness, seasonality, and rhythmicity with suicidal ideation in 103 participants with depression, insomnia, and suicidality within a larger 8-week double-blinded randomized control trial primarily examining whether cautious use of zolpidem extended-release or placebo reduced suicidal ideation. All participants additionally received an open-label selective serotonin reuptake inhibitor. Methodological strengths of the current analyses included consideration of multiple sleep-wake constructs, adjustment for relevant covariates, investigation of relationships over the course of treatment, and use of both self-report measures and objective measurement with actigraphy.

RESULTS

Over the course of treatment, self-reported eveningness and greater insomnia severity were independently correlated with greater suicidal ideation, whereas actigraphic delayed sleep timing was related to suicidal ideation at a trend level. At the end of treatment, those with greater suicidal ideation demonstrated lower actigraphic activity levels. There were no significant relationships between self-reported seasonality and actigraphic measures of sleep disturbance and suicidality.

CONCLUSIONS

Self-reported delays in sleep timing, objectively lower activity levels, and self-reported insomnia severity correlated independently with greater suicidal ideation in those with depression, insomnia, and suicidality. These exploratory findings highlight the need to consider sleep-wake constructs more broadly in those with suicidality in future research studies in order to improve more definitively both assessment and intervention efforts.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Reducing Suicidal Ideation through Insomnia Treatment; URL: https://clinicaltrials.gov/ct2/show/NCT01689909; Identifier: NCT01689909 Rumble ME, McCall MV, Dickson DA, Krystal AD, Rosenquist PB, Benca RM. An exploratory analysis of the association of circadian rhythm dysregulation and insomnia with suicidal ideation over the course of treatment in individuals with depression, insomnia, and suicidal ideation. J Clin Sleep Med. 2020;16(8):XXX-XXX.

Chronotypes and affective disorders: A clock for mood?

Affective disorders are often accompanied by circadian rhythm disruption and the major symptoms of mental illness occur in a rhythmic manner. Chronotype, also known as circadian preference for rest or activity, is believed to exert a substantial influence on mental health. Here, we review the connection between chronotypes and affective disorders, and discuss the potential underlying mechanisms between these two phenomena.

Evening chronotype as a discrete clinical subphenotype in bipolar disorder

OBJECTIVE

Our aim was to investigate evening chronotype, a proxy marker of circadian system dysfunction, as a clinical subphenotype in bipolar disorder (BD).

METHODS

In this cross-sectional study, 773 BD participants and 146 control subjects were evaluated using the Structured Clinical Interview for DSM-IV and a set of questionnaires. Chronotype was determined using item-5 from the reduced Morningness-Eveningness Questionnaire. Univariate analyses and regression models were used to compare evening and non-evening chronotype in BD and chronotype association with clinical variables.

RESULTS

Overall, 205 (27%) of BD patients reported an evening chronotype. Evening chronotype was higher in a matched sub-sample of BD patients (n = 150) than in controls (24% and 5% respectively, OR=5.4, p<0.01). Compared to those with non-evening chronotypes, BD patients with an evening chronotype were younger, had an earlier age of onset of BD, and had more prior depressive and manic episodes, higher rates of rapid cycling, past suicide attempts, more comorbid anxiety and substance use disorders. Multivariate regression showed age, prior suicide attempts, and co-occurring substance use disorder were associated with evening chronotype (OR range of 0.97 to1.59). Hypertension, migraine, asthma, and obstructive sleep apnea were significantly associated with evening chronotype (OR range of 1.56 to 2.0).

LIMITATION

Limitations include a cross-sectional study design that precludes establishing causality. Analyses did not control for medication use. Younger participant age may prevent evaluation of associations with late-life illnesses.

CONCLUSIONS

Evening chronotype may be a discrete clinical subphenotype in BD and circadian dysfunction a shared pathophysiological mechanism between psychopathology and medical morbidity.

Circadian regulation of depression: A role for serotonin

Synchronizing circadian (24 h) rhythms in physiology and behavior with the environmental light-dark cycle is critical for maintaining optimal health. Dysregulation of the circadian system increases susceptibility to numerous pathological conditions including major depressive disorder. Stress is a common etiological factor in the development of depression and the circadian system is highly interconnected to stress-sensitive neurotransmitter systems such as the serotonin (5-hydroxytryptamine, 5-HT) system. Thus, here we propose that stress-induced perturbation of the 5-HT system disrupts circadian processes and increases susceptibility to depression. In this review, we first provide an overview of the basic components of the circadian system. Next, we discuss evidence that circadian dysfunction is associated with changes in mood in humans and rodent models. Finally, we provide evidence that 5-HT is a critical factor linking dysregulation of the circadian system and mood. Determining how these two systems interact may provide novel therapeutic targets for depression.

Chronotype and Psychiatric Disorders

PURPOSE OF REVIEW

Chronotype, reflecting interindividual differences in daily activity patterns and sleep-wake cycles, is intrinsically connected with well-being. Research indicates increased risk of many adverse mental health outcomes for evening-type individuals. Here, we provide an overview of the current evidence available on the relationship between chronotype and psychiatric disorders.

RECENT FINDINGS

The association between eveningness and depression is well established cross-sectionally, with preliminary support from longitudinal studies. The mechanisms underlying this relationship warrant further research; deficient cognitive-emotional processes have recently been implicated. Eveningness is associated with unhealthy lifestyle habits, and the propensity of evening types to addiction has been recognized. Chronotype may also be implicated in disordered eating.

SUMMARY

Eveningness is associated with depression-including seasonal affective disorder (SAD)-and substance dependence, while support for a relation with anxiety disorders and psychosis is lacking. In bipolar disorder, chronotype is linked to depression but not mania. Eveningness is also related to sleep disturbances and poor lifestyle habits, which may increase risk for psychiatric disorders.

Morningness-Eveningness questionnaire in bipolar disorder

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

Eveningness is associated with poor sleep quality and negative affect in obsessive-compulsive disorder

Background Obsessive-compulsive disorder (OCD) is characterized by intrusive thoughts and repetitive behaviors that severely encumber daily functioning. OCD patients seem to exhibit sleep disturbances, especially delayed bedtimes that reflect disrupted circadian rhythmicity. Morningness-eveningness is a fundamental factor reflecting individual variations in diurnal preferences related to sleep and waking activities. Eveningness reflecting a delayed sleep-wake timing has repeatedly been associated with sleep problems and negative affect (NA). Therefore, the aim of this study was to examine the associations between morningness-eveningness, sleep complaints, and symptom severity in OCD patients and compared with a mixed psychiatric control group. Materials and methods The data of 49 OCD and 49 mixed psychiatric inpatients (with unipolar depression and anxiety disorders) were analyzed. Patients completed questionnaires regarding morningness-eveningness, sleep quality, nightmare frequency, depression, anxiety, and affective states. Obsessive and compulsive symptom severity was also assessed within the OCD group by clinician-rated scales. Results Eveningness preference was associated with impaired sleep quality and higher NA in OCD patients. In addition, impaired sleep quality showed a moderate correlation with anxiety and strong correlations with depressive symptoms and NA. Interestingly, in the mixed psychiatric group, eveningness was not linked to NA, and sleep quality also showed weaker associations with depressive symptoms and NA. Within the OCD group, eveningness preference was predictive of poorer sleep quality regardless the influence of depressive symptoms. Conclusion Our findings suggest that eveningness and sleep complaints are predictive of affective dysfunctions, and should be carefully considered in the evaluation and treatment of OCD patients.

The relationship of person-specific eveningness chronotype, greater seasonality, and less rhythmicity to suicidal behavior: A literature review

BACKGROUND

Epidemiological data have demonstrated seasonal and circadian patterns of suicidal deaths. Several reviews and meta-analyses have confirmed the relationship between sleep disturbance and suicidality. However, these reviews/meta-analyses have not focused on seasonal and circadian dysfunction in relation to suicidality, despite the common presence of this dysfunction in patients with mood disorders. Thus, the current literature review analyzed studies investigating person-specific chronotype, seasonality, and rhythmicity in relation to suicidal thoughts and behaviors.

METHODS

Study authors reviewed articles related to individual-level chronotype, seasonality, and rhythmicity and suicidality that were written in English and not case reports or reviews.

RESULTS

This review supports a relationship between an eveningness chronotype, greater seasonality, and decreased rhythmicity with suicidal thoughts and behaviors in those with unipolar depression, as well as in other psychiatric disorders and in children/adolescents.

LIMITATIONS

These findings need to be explored more fully in mood disordered populations and other psychiatric populations, in both adults and children, with objective measurement such as actigraphy, and with chronotype, seasonality, and rhythmicity as well as broader sleep disturbance measurement all included so the construct(s) most strongly linked to suicidality can be best identified.

CONCLUSIONS

Eveningness, greater seasonality, and less rhythmicity should be considered in individuals who may be at risk for suicidal thoughts and behaviors and may be helpful in further tailoring assessment and treatment to improve patient outcome.

Genetic Influences on Evening Preference Overlap with Those for Bipolar Disorder in a Sample of Mexican Americans and American Indians

Diurnal preference (e.g., being an owl or lark) has been associated with several psychiatric disorders including bipolar disorder (BP), major depressive disorder, and substance use disorders. Previous large-scale genome-wide association studies (GWAS) aimed at identifying genetic influences on diurnal preference have exclusively included subjects of European ancestry. This study examined the genetic architecture of diurnal preference in two minority samples: a young adult sample of Mexican Americans (MAs), and a family-based sample of American Indians (AIs). Typed or imputed variants from exome chip data from the MA sample and low pass whole-genome sequencing from the AI cohort were analyzed using a mixed linear model approach for association with being an owl, as defined by a usual bedtime after 23:00 hrs. Genetic risk score (GRS) profiling detected shared genetic risk between evening preference and related disorders. Four variants in KIAA1549 like (KIAA1549L), a gene previously associated with attempted suicide in bipolar patients, were suggestively associated with being an owl at p < 1.82E-05; post hoc analyses showed the top variant trending in both the MA and AI cohorts at p = 2.50E-05 and p = .030, respectively. Variants associated with BP at p < .03 from the Psychiatric Genomics Consortium nominally predicted being an owl in the MA/AI cohort at p = .012. This study provides some additional evidence that genetic risk factors for BP also confer risk for being an owl in MAs/AIs and that evening preference may be a useful endophenotype for future studies of BP.

Suicidality in sleep disorders: prevalence, impact, and management strategies

Sleep disturbances are associated with suicide-related thoughts and behaviors, and the incidence of sleep concerns and suicide has increased recently in the US. Most published research exploring the sleep-suicidality relation is focused on select sleep disorders, with few reviews offering a comprehensive overview of the sleep-suicidality literature. This narrative review broadly investigates the growing research literature on sleep disorders and suicidality, noting the prevalence of suicide ideation and nonfatal and fatal suicide attempts, the impact of several sleep disorders on suicide risk, and potential sleep-disorder management strategies for mitigating suicide risk. Aside from insomnia symptoms and nightmares, there exist opportunities to learn more about suicide risk across many sleep conditions, including whether sleep disorders are associated with suicide risk independently of other psychiatric conditions or symptoms. Generally, there is a lack of randomized controlled trials examining the modification of suicide risk via evidence-based sleep interventions for individuals with sleep disorders.

The relationship between chronotype and depressive symptoms: A meta-analysis

BACKGROUND

Expanding our understanding of the factors that influence depression is crucial for prognosis and treatment. In light of increasing evidence of an association between disrupted circadian rhythms and affective symptoms, a meta-analysis was used to examine the relationship between an eveningness chronotype and depression.

METHODS

Electronic searches of the PsycINFO, Medline, Scopus, and Google Scholar databases were conducted in February 2016. Relevant reviews, related journals, and reference lists were manually searched. Statistical data were reported or transformed to a Fisher's z correlational coefficient for effect size analysis.

RESULTS

Data from 36 studies (n =15734) met the inclusion criteria and were analysed under a random effects model. Nearly all included studies utilised the Composite Scale of Morningness (CSM) or the Morningness-Eveningness Questionnaire (MEQ) as a measure of chronotype. Overall effect size from 58 effect sizes was small (z=-.20; 95% CI: -.18 to -.23). Effect sizes based on the CSM were significantly larger than those based on the MEQ. There was no evidence of publication bias.

LIMITATIONS

The number of studies comparing different mood disorders or the potential moderating effects of gender and age were too few to draw conclusions regarding their respective effect sizes. Future research should utilise longitudinal designs to draw causal inferences on the directionality of this relationship.

CONCLUSIONS

Findings from this meta-analysis indicate an eveningness orientation is somewhat associated with more severe mood symptoms. Chronobiological approaches may contribute to the prevention and treatment of depressive disorders.

ARNTL, CLOCK and PER3 polymorphisms - links with chronotype and affective dimensions

Recently, seven single nucleotide polymorphisms (SNPs) of ARNTL, TIM and PER3 genes were found associated with affective temperaments in bipolar disorder patients. This study aimed to test whether a) the same associations appear in a non-clinical sample; b) the SNPs are related to other affective dimensions; c) the SNPs underpin the associations between chronotype and affective temperaments/dimensions. Three hundred thirty-eight university students completed the Temperament Scale of Memphis, Pisa, Paris and San Diego Auto-questionnaire, the Centre for Epidemiological Studies Depression Scale, the Perceived Stress Scale, the General Health Questionnaire, the Seasonal Pattern Assessment Questionnaire and the Composite Scale of Morningness. Seven SNPs of the ARNTL, TIM and PER3 genes were genotyped. According to nominal significance, ARNTL rs7107287 was associated with a cyclothymic temperament, depressive and stress symptoms, general mental health and perceived negative impact of seasonality, while TIM rs10876890 was associated with a hyperthymic temperament, and the TIM rs2291738 was associated with chronotype. Different SNPs were related to chronotype and affective temperaments/dimensions, and therefore, they seem to not underpin relationships between chronotype and affective dysfunction, that is, in the present study, eveningness was related to dysthymic, cyclothymic and irritable temperaments, more symptoms of depression, stress, worse mental health and a negative impact of seasonality, while morningness was related to hyperthymic temperament. The SNPs associations need further replication given that they did not achieve Bonferroni criteria of significance accounting for the number of polymorphisms considered and tests conducted.

Nightmares as predictors of suicide: an extension study including war veterans

Nightmares are intensive dreams with negative emotional tone. Frequent nightmares can pose a serious clinical problem and in 2001, Tanskanen et al. found that nightmares increase the risk of suicide. However, the dataset used by these authors included war veterans in whom nightmare frequency - and possibly also suicide risk - is elevated. Therefore, re-examination of the association between nightmares and suicide in these data is warranted. We investigated the relationship between nightmares and suicide both in the general population and war veterans in Finnish National FINRISK Study from the years 1972 to 2012, a dataset overlapping with the one used in the study by Tanskanen et al. Our data comprise 71,068 participants of whom 3139 are war veterans. Participants were followed from their survey participation until the end of 2014 or death. Suicides (N = 398) were identified from the National Causes of Death Register. Frequent nightmares increase the risk of suicide: The result of Tanskanen et al. holds even when war experiences are controlled for. Actually nightmares are not significantly associated with suicides among war veterans. These results support the role of nightmares as an independent risk factor for suicide instead of just being proxy for history of traumatic experiences.

Solar radiation increases suicide rate after adjusting for other climate factors in South Korea

OBJECTIVE

Previous studies have indicated that suicide rates have significant seasonal variations. There is seasonal discordance between temperature and solar radiation due to the monsoon season in South Korea. We investigated the seasonality of suicide and assessed its association with climate variables in South Korea.

METHOD

Suicide rates were obtained from the National Statistical Office of South Korea, and climatic data were obtained from the Korea Meteorological Administration for the period of 1992-2010. We conducted analyses using a generalized additive model (GAM). First, we explored the seasonality of suicide and climate variables such as mean temperature, daily temperature range, solar radiation, and relative humidity. Next, we identified confounding climate variables associated with suicide rate. To estimate the adjusted effect of solar radiation on the suicide rate, we investigated the confounding variables using a multivariable GAM.

RESULTS

Suicide rate showed seasonality with a pattern similar to that of solar radiation. We found that the suicide rate increased 1.008 times when solar radiation increased by 1 MJ/m² after adjusting for other confounding climate factors (P < 0.001).

CONCLUSION

Solar radiation has a significant linear relationship with suicide after adjusting for region, other climate variables, and time trends.

Sleep and circadian alterations in people at risk for bipolar disorder: A systematic review

BACKGROUND

Sleep and circadian abnormalities have been mostly demonstrated in bipolar patients. However, it is not clear whether these alterations are present in population at high risk for bipolar disorder (BD), indicating a possible risk factor for this condition.

OBJECTIVE

This systematic review aims to define current evidence about sleep and rhythm alterations in people at risk for BD and to evaluate sleep and circadian disorders as risk factor for BD.

METHODS

The systematic review included all articles about the topic until February 2016. Two researchers performed an electronic search of PubMed and Cochrane Library. Keywords used were 'sleep' or 'rhythm' or 'circadian' AND 'bipolar disorder' or 'mania' or 'bipolar depression' AND 'high-risk' or 'risk'.

RESULTS

Thirty articles were analyzed (7451 participants at risk for BD). Sleep disturbances are frequent in studies using both subjective measures and actigraphy. High-risk individuals reported irregularity of sleep/wake times, poor sleep and circadian rhythm disruption. Poor sleep quality, nighttime awakenings, and inadequate sleep are possible predictive factors for BD. A unique study suggested that irregular rhythms increase risk of conversion. People at risk for BD showed high cortisol levels in different times of day. Studies about anatomopathology, melatonin levels, inflammatory cytokines and oxidative stress were not identified. The most important limitations were differences in sleep and rhythm measures, heterogeneity of study designs, and lack of consistency in the definition of population at risk.

CONCLUSION

Sleep and circadian disturbances are common in people at risk for BD. However, the pathophysiology of these alterations and the impact on BD onset are still unclear.

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.

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.

Circadian preference links to depression in general adult population

BACKGROUND

Preference to time the daily activities towards the evening hours has been associated with a greater likelihood for depression in earlier studies consisting of relatively small samples.

METHODS

In the current study, we analyzed the relationship between chronotype and depression using a combined population-based sample of 10,503 Finnish adults aged 25 to 74 years from the two national FINRISK 2007 and 2012 health examination studies.

RESULTS

Our results confirmed that eveningness was significantly associated with the increased odds for a diagnosed depressive disorder, antidepressant medication, and depressive symptoms (p<0.0001 for each), after controlling for a range of depression-attributed and potential confounding factors. Regardless of depressive symptoms, Evening-types had lower systolic and diastolic blood pressures, a smaller waist circumference, and a lower body weight than other chronotypes.

LIMITATIONS

A limitation to our study is that the assessment of chronotype and information about depression was based on the self-report information only. However, the big population-based sample, which is derived from a national health examination survey, is a major strength of our study.

CONCLUSIONS

In conclusion, our study is in line the results from the previous, smaller sample size studies confirming that Evening-types have higher risk for depression than other chronotypes. This risk is elevated even among those Evening-types with sufficient amount of sleep.