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.

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.

Circadian preference and mental health outcomes in youth: A systematic review and meta-analysis

Youth is a vulnerable developmental period associated with an increased preference for eveningness and risk for developing psychopathology. Growing evidence suggests a link between eveningness and poorer mental health outcomes, but the findings in the current literature are inconsistent, and a comprehensive synthesis of evidence in this area remains lacking. This meta-analysis aimed to 1) synthesise the existing evidence on the association between circadian preference and mental health outcomes in youths and 2) explore potential sleep-related factors that may moderate the relationship between circadian preference and mental health outcomes. A systematic search of five electronic databases resulted in 81 observational studies included in the review. Eveningness was found to be significantly associated with general mental health (r = 0.20), mood-related disturbances (r = 0.17), and anxiety problems (r = 0.13). The qualitative review also identified that eveningness was associated with greater risks for psychotic symptoms and maladaptive eating behaviours. These findings highlighted the need to consider circadian preference in the clinical management of youth mental health problems. Further research is needed to examine the efficacy of a circadian-focused intervention in the context of youth mental health.

The relationship between chronotype, dispositional mindfulness and suicidal ideation among medical students: mediating role of anxiety, insomnia and social dysfunction

The aim of the study was to assess whether chronotype and subjective amplitude may predict suicidal ideation independently of mindfulness, and whether anxiety/insomnia and social dysfunction may be mediators of the relationship between chronotype and suicidal thoughts among medical students. The study group comprised 600 students of the medical faculties (191 men and 409 women), with a mean (SD, range) age of 21.94 (1.81, 18-31) years. The participants completed the Chronotype Questionnaire, the Five Facet Mindfulness Questionnaire (FFMQ) and the General Health Questionnaire (GHQ-28). Two items from GHQ-28 depression scale were extracted to measure suicidal ideation. The FFMQ score correlated negatively with the suicidal ideation score. The total effect of chronotype was insignificant when controlled for FFMQ. In the case of indirect effects, subjective amplitude score predicted suicidal ideation via both anxiety/insomnia and social dysfunction scores. The FFMQ score predicted suicidal ideation only via the social dysfunction scale. The direct effect of subjective amplitude was insignificant. Our findings indicate that the flexibility (or rigidity) of circadian rhythm may be linked to the intensity of experienced suicidal ideation, but only via anxiety/insomnia and social dysfunction, independently of mindfulness and morningness-eveningness.

Circadian preference in young adults: Associations with sleep and mental health outcomes from a national survey of Norwegian university students

Individual preferred timing of sleep and activity patterns, known as circadian preference, ranges from definitely morning types to definitely evening types. Being an evening type has been linked to adverse sleep and mental health outcomes. This study aimed to explore the associations between circadian preference and self-reported sleep, depression, anxiety, quality of life, loneliness, and self-harm/suicidal thoughts. Data stem from a national survey of students in higher education in Norway (the SHoT-study). All 169,572 students in Norway were invited to participate, and 59,554 students (66.5% women) accepted (response rate = 35.1%). Circadian preference was associated with sleep and mental health outcomes in a dose-response manner. For both genders, being an evening type (either definitely evening or more evening than morning) was associated with an increase in age-adjusted relative risk (RR-adjusted; range = 1.44 to 2.52 vs. 1.15 to 1.90, respectively) across all outcomes compared with definitely morning types. Overall, the present study provides further evidence that evening circadian preference is associated with adverse sleep and mental health outcomes in young adults. As such, future efforts to improve sleep and mental health in young adults should consider their circadian preferences.

Circadian Rhythms in Mood Disorders

Altered behavioral rhythms are a fundamental diagnostic feature of mood disorders. Patients report worse subjective sleep and objective measures confirm this, implicating a role for circadian rhythm disruptions in mood disorder pathophysiology. Molecular clock gene mutations are associated with increased risk of mood disorder diagnosis and/or severity of symptoms, and mouse models of clock gene mutations have abnormal mood-related behaviors. The mechanism by which circadian rhythms contribute to mood disorders remains unknown, however, circadian rhythms regulate and are regulated by various biological systems that are abnormal in mood disorders and this interaction is theorized to be a key component of mood disorder pathophysiology. A growing body of evidence has begun defining how the interaction of circadian and neurotransmitter systems influences mood and behavior, including the role of current antidepressants and mood stabilizers. Additionally, the hypothalamus-pituitary-adrenal (HPA) axis interacts with both circadian and monoaminergic systems and may facilitate the contribution of environmental stressors to mood disorder pathophysiology. The central role of circadian rhythms in mood disorders has led to the development of chronotherapeutics, which are treatments designed specifically to target circadian rhythm regulators, such as sleep, light, and melatonin, to produce an antidepressant response.

Eveningness, depression and cardiovascular reactivity to acute psychological stress: A mediation model

The psychological pathways linking depression to blunted cardiovascular reactivity (CVR) are still being elucidated. The purpose of the present study was to test whether the association between eveningness, a diurnal/sleep-wake preference and CVR would be mediated by depressive symptoms. One hundred and eighty-two healthy young adults completed measures of morningness/eveningness (the Morningness-Eveningness Questionnaire; MEQ-SA), depressive symptoms (Hospital Anxiety and Depression Scale; HADS) and had their blood pressure and heart rate monitored throughout a standardised stress testing protocol. Results indicated that depressive symptoms were negatively associated with systolic blood pressure (SBP) but not diastolic blood pressure (DBP) or heart rate (HR) reactions to the stress task. Eveningness was also negatively associated with both SBP and DBP, but not HR. As such, those who reported increased depressive symptomology, and higher scores on eveningness displayed a more blunted cardiovascular response. Furthermore, the latter relationship was mediated by depressive symptoms such that those reporting higher scores on eveningness also reported increased depressive symptomology and this resulted in blunted CVR for SBP. These findings withstood adjustment for several confounding factors including time of testing. In conclusion, the present findings highlight the importance of considering eveningness when looking at the depression-blunted CVR relationship.

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.

Diurnal preference and depressive symptomatology: a meta-analysis

Eveningness, a preference for later sleep and rise times, has been associated with a number of negative outcomes in terms of both physical and mental health. A large body of evidence links eveningness to Major Depressive Disorder (MDD). However, to date, evidence quantifying this association is limited. The current meta-analysis included 43 effect sizes from a total 27,996 participants. Using a random-effects model it was demonstrated that eveningness is associated with a small effect size (Fisher's Z = - 2.4, 95% CI [- 0.27. - 0.21], p < 0.001). Substantial heterogeneity between studies was observed, with meta-regression analyses demonstrating a significant effect of mean age on the association between diurnal preference and depression. There was also evidence of potential publication bias as assessed by visual inspection of funnel plots and Egger's test. The association between diurnal preference and depression is small in magnitude and heterogenous. A better understanding of the mechanistic underpinnings linking diurnal preference to depression and suitably powered prospective studies that allow causal inference are required.

Chronotype, Sleep, and Depressive Symptoms Among Chinese College Students: A Cross-Sectional Study

Objective: To describe the prevalence of chronotype and depressive symptoms among Chinese college students and to examine the association between chronotype and depressive symptoms.

Methods: From April to May 2019, a cross-sectional survey was conducted among 1,179 Chinese college students from 2 universities in Anhui and Jiangxi provinces. A total of 1,135 valid questionnaires were collected, the valid response rate was 98.6%. The questionnaire investigated age, gender, major, height, weight, only child status, living place, self-reported family economy, and self-reported study burden. The chronotype was assessed by the Morning and Evening Questionnaire (MEQ). Depressive symptoms and sleep quality were evaluated by the Patient Health Questionnaire 9 (PHQ-9) and the Pittsburgh Sleep Quality Index (PSQI), respectively. A Chi-square test was used to examine the proportion of depressive symptoms among Chinese college students with different demographic characteristics. The generalized linear model was used to analyze the relationships between chronotype and depressive symptoms.

Results: The proportion of morning types (M-types), neutral types (N-types), and evening types (E-types) of college students were 18.4, 71.1, and 10.5%, respectively. The proportion of mild depression, moderate depression, and moderate to severe depression of participants were 32.4, 6.0, and 4.2%, respectively. Compared to the M-types, after controlled for age, gender, major, sleep quality, self-reported study burden, father's education level, and self-reported family economy, depressive symptoms were positively correlated with E-types (OR = 2.36, 95% CI: 1.49–3.73).

Conclusions: There was a significant association between chronotype and depressive symptoms among Chinese college students. Further longitudinal studies were needed to clarify the causal relationship between chronotype and depressive symptoms.

Regulação molecular do ritmo circadiano e transtornos psiquiátricos: uma revisão sistemática

RESUMO Objetivo O artigo possui como objetivo investigar os genes relógio que estão mais associados com os transtornos psiquiátricos, as funções e localizações desses genes, assim como investigar o principal transtorno, método e modelo considerados nas análises. O trabalho busca resumir os achados e discutir o impacto dessas pesquisas no conhecimento científico. Métodos Esta revisão utilizou-se de uma metodologia sistemática (Prospero; ID 152031) e seguiu as diretrizes PRISMA. A busca dos estudos foi realizada nas bases de dados PubMed/MEDLINE e Scientific Eletronic Library Online e foram utilizados os termos do Medical Subject Headings Terms . Foram selecionados estudos quantitativos com resultados conclusivos referentes à associação de transtornos psiquiátricos com a regulação molecular do ritmo circadiano. As informações úteis foram extraídas e utilizadas para a elaboração de gráficos e tabelas. Resultados Foram incluídos 24 artigos em nosso estudo. Observou-se que o transtorno bipolar consistiu no transtorno psiquiátrico mais abordado (40% dos estudos); a nacionalidade polonesa dos participantes também se destacou em 39% dos trabalhos. Adicionalmente, o gene PER foi o mais estudado (25%) e o córtex cerebral foi a principal região em que os genes relógio avaliados se expressam (34%). A PCR comum mostrou ser o método mais utilizado (38%) e o metabolismo da serotonina mostrou ser a principal função desempenhada pelos produtos gênicos (16%). Conclusões Em conjunto, os resultados sugerem que o transtorno bipolar consiste no distúrbio psiquiátrico mais prevalente entre as pesquisas relacionadas aos genes circadianos, expressos principalmente no córtex cerebral de humanos, em especial o gene PER .

Heterogeneity of sleep quality in relation to circadian preferences and depressive symptomatology among major depressive patients

BACKGROUND

The current study aimed at investigating the latent dimensional structure of sleep quality as indexed by the seven components of the Pittsburgh Sleep Quality Index (PSQI), as well as latent covariance structure between sleep quality, circadian preferences and depressive symptoms.

METHODS

Two hundred twenty-five patients with major depressive disorder (MDD), with an average age of 29.92 ± 10.49 years (aged between 17 and 63), participated in the study. The PSQI, Morningness-Eveningness Questionnaire (MEQ) and Beck Depression Inventory (BDI) were administered to participants. Four sets of latent class analyses were subsequently run to obtain optimal number of latent classes best fit to the data.

RESULTS

Mixture models revealed that sleep quality is multifaceted in MDD. The data best fit to four-latent-class model: Poor Habitual Sleep Quality (PHSQ), Poor Subjective Sleep Quality (PSSQ), Intermediate Sleep Quality (ISQ), and Good Sleep Quality (GSQ). MDD patients classified into GSQ latent class (23.6%) reported the lowest depressive symptoms and were more prone to morningness diurnal preferences compared to other three homogenous sub-groups. Finally, the significant association between eveningness diurnal preferences and depressive symptomatology was significantly mediated by poor sleep quality.

LIMITATION

The cross-sectional nature of the study and the lack of an objective measurement of sleep such as polysomnography recordings was the most striking limitation of the study.

CONCLUSIONS

We concluded sleep quality in relation to circadian preferences and depressive symptoms has a heterogeneous nature in MDD.

Chronotype and Mental Health: Recent Advances

PURPOSE OF REVIEW

Evening chronotype is increasingly recognized as a correlate of, and perhaps a contributor to, mental illness. The current review evaluates recent evidence for the association between chronotype and mental illness and putative mechanisms underlying the association, while highlighting methodological advances and areas of research that are relatively under-examined in the literature.

RECENT FINDINGS

While evening chronotype is most consistently associated with severity of mood disorder symptoms, emerging evidence implicates evening chronotype as a transdiagnostic correlate of substance use severity, anxiety symptoms, attentional difficulties, and maladaptive behaviors such as aggression. Longitudinal studies point to the possibility that evening chronotype precedes problematic substance use, depression, and anxiety. Neural processes related to reward and affective regulation may underlie associations between evening chronotype and illness. The literature on chronotype and mental illness has evolved to (1) include associations with a broader range of psychiatric symptom profiles; (2) explore underlying mechanisms; and (3) expand on earlier research using objective measures and more sophisticated study designs. In addition to further mechanistic research, additional work is needed to examine the stability and key subcomponents of the chronotype construct, as well as more attention to pediatric and special populations. This research is needed to clarify the chronotype-mental health relationship, and to identify how, when, and what aspects of chronotype can be targeted via therapeutic interventions.

Clinical chronobiology: a timely consideration in critical care medicine

A fundamental aspect of human physiology is its cyclical nature over a 24-h period, a feature conserved across most life on Earth. Organisms compartmentalise processes with respect to time in order to promote survival, in a manner that mirrors the rotation of the planet and accompanying diurnal cycles of light and darkness. The influence of circadian rhythms can no longer be overlooked in clinical settings; this review provides intensivists with an up-to-date understanding of the burgeoning field of chronobiology, and suggests ways to incorporate these concepts into daily practice to improve patient outcomes. We outline the function of molecular clocks in remote tissues, which adjust cellular and global physiological function according to the time of day, and the potential clinical advantages to keeping in time with them. We highlight the consequences of "chronopathology", when this harmony is lost, and the risk factors for this condition in critically ill patients. We introduce the concept of "chronofitness" as a new target in the treatment of critical illness: preserving the internal synchronisation of clocks in different tissues, as well as external synchronisation with the environment. We describe methods for monitoring circadian rhythms in a clinical setting, and how this technology may be used for identifying optimal time windows for interventions, or to alert the physician to a critical deterioration of circadian rhythmicity. We suggest a chronobiological approach to critical illness, involving multicomponent strategies to promote chronofitness (chronobundles), and further investment in the development of personalised, time-based treatment for critically ill patients.

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.

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.

Suicidal behavior in the context of disrupted rhythmicity in bipolar disorder-Complementary research of clock genes with suicide risks factors and course of disease

Former findings indicate that suicidal behavior in bipolar disorder is associated with clock genes. Additionally, numerous non-genetic risk factors are potentially associated with suicidal behavior. Therefore, we conducted an analysis of the relationship between clock genes (as distal risk factors) with clinical characteristics and the course of bipolar disorder. We also tried to obtain a predictive model for suicide attempts based on clinical and genetic data. We found associations between selected polymorphisms and.

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.

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

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

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.

Chronotypes in patients with nonseasonal depressive disorder: Distribution, stability and association with clinical variables

The individual's chronotype is regarded as rather stable trait with substantial heritability and normal distribution of the "morningness-eveningness" dimension in the general population. Eveningness has been related to the risk of developing affective, particularly depressive, disorders. However, age and other sociobiological factors may influence chronotypes. The present study investigated the distribution, stability, and clinical correlates of chronotype and morningness-eveningness in hospitalized patients with affective disorder. Chronotype was assessed with the morningness-eveningness questionnaire (MEQ) in 93 patients with nonseasonal depressive syndrome (85% major depression; 15% depressive adjustment disorder) after admission, and in 19 patients again before discharge. Distribution, stability and correlations of MEQ scores with clinical variables were calculated. Additionally, a literature analysis of chronotype distributions in samples of nondepressed persons and patients with nonseasonal depression was carried out. MEQ scores (mean 49 ± 11, range 23-75, higher scores indicate morningness) in 93 acutely depressed inpatients (age 41 ± 14 years, range 18-75 years; 63% women; hospitalization 48 ± 22 days; BDI-II 32 ± 11) were normally distributed (Shapiro-Wilk test; W = 0.993, p = 0.920) with 59.1% intermediate types, 19.4% evening types, and 21.5% morning types. MEQ change scores from admission to discharge were nonsignificant (-1.3 ± 5.0; paired t-test, t18 = -1.09; p = 0.29) despite significantly improved depression scores (-19.4 ± 7.6; paired t-test, t18 = 11.2, p < 0.001). Age (r = 0.24), and depression scores (r = -0.21) correlated significantly (p < 0.05) with MEQ scores; associations with sex and hospitalization duration were nonsignificant. The present study and literature findings revealed that the frequency of evening types is not clearly elevated in depression, but morning types are less frequent compared to healthy samples (p < 0.001). Morningness-eveningness scores were normally distributed and stable in depressive inpatients. In line with previous findings, but contrary to theoretical assumptions, evening types were not overrepresented in depressed patients. Additionally, relatively less morning types and more intermediate types were found in depressed patients. Future studies should focus on transitions from morning to intermediate types as a tentative risk or correlate of emerging depression.