Associations Between Chronotypes, Psychopathology, and Personality Among Incoming College Students

Is There an Increase in Possible Sleep Bruxism in Children Over Time? A Longitudinal Study

BACKGROUND

Bruxism is a behaviour that has several consequences in an individual's life, especially when it starts in childhood. However, bruxism can be a potential protective factor, which is an attribute that reduces the chance of a negative health outcome.

OBJECTIVES

To evaluate the incidence of sleep bruxism (SB) and dental wear in children and adolescents.

MATERIALS AND METHODS

This longitudinal study began in 2014 and 2016 (baseline) with initial 1816 children followed for 5 and 3 years, respectively. The follow-up data collection started in 2019. The diagnosis of SB was parents report (baseline) and self-report (follow-up) due to age groups of each phase, and questions related to symptoms of SB were collected. Five calibrated examiners (kappa >0.7) collected the clinical data. The clinical variables were dental erosion and dental wear. Contextual, individual, behaviour and clinical characteristics were collected. A multilevel logistic regression model was used to investigate the association of contextual, individual, behaviour and clinical characteristics with SB. Poisson regression for repeated measures was performed to evaluate the incidence of SB and dental wear (incidence rate ratio-IRR and confidence interval-95% CI).

RESULTS

Two hundred and fifty-three children and adolescents answered questionnaires and were clinically examined. The mean age of the follow-up in 2019 was 11.25 years old (±2.19). There was no increase in the incidence of SB (95% CI: 0.74-1.35). Children/adolescents had a 2.2 higher risk to present dental wear (95% CI: 1.89-2.60). SB at the follow-up was associated with the contextual variable, earache, erosion and awake bruxism.

CONCLUSIONS

In this population, children with SB remained with this behaviour and showed higher dental wear over the years.

The relationship between morningness-eveningness and naturalness bias

The naturalness bias in which people perceive natural items to be safer, healthier, and better than synthetic alternatives has been found to be associated with numerous individual difference variables (e.g. connectedness to nature and religiosity). However, no research has examined the role of morningness-eveningness in influencing preferences for naturalness. Here, we propose that evening individuals may exhibit a weaker preference for naturalness compared to morning individuals due to their greater exposure to artificial lighting, technology, and stimuli. To systematically test our theoretical perspective, we conducted three complementary and high-powered studies. In an online survey (Study 1), student participants with a stronger evening orientation displayed a diminished preference for natural drugs compared to those with a morning orientation. Using a sample of community adults, Study 2 replicated the findings of Study 1 in a real-world, behavioral context. Study 3 examined the relationship between morningness-eveningness and preference for naturalness within the domain of beverages. The results revealed that individuals with an evening-orientation had decreased odds of selecting natural water without minerals. Taken together, the findings suggest that an individual's diurnal preference toward eveningness may have implications for their bias toward and perception of naturalness across various domains.

Circadian markers as a predictor of response in the treatment of depression-A systematic review

Despite many available treatment options for depression, response rates remain suboptimal. To improve outcome, circadian markers may be suitable as markers of treatment response. This systematic review provides an overview of circadian markers that have been studied as predictors of response in treatment of depression. A search was performed (EMBASE, PUBMED, PSYCHINFO) for research studies or articles, randomized controlled trials and case report/series with no time boundaries on March 2, 2024 (PROSPERO: CRD42021252333). Other criteria were; an antidepressant treatment as intervention, treatment response measured by depression symptom severity and/or occurrence of a clinical diagnosis of depression and assessment of a circadian marker at baseline. 44 articles, encompassing 8,772 participants were included in the analysis. Although additional research is needed with less variation in types of markers and treatments to provide definitive recommendations, circadian markers, especially diurnal mood variation and chronotype, show potential to implement as response markers in the clinic.

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.

Relationship between chronotypes and aggression in adolescents: a cross-sectional study

BACKGROUND

This study aimed to investigate the relationship between chronotypes and aggression in adolescents.

METHODS

A cross-sectional study was conducted on 755 primary and secondary school students aged 11-16 years in rural areas of Ningxia Province, China. The Chinese version of the Buss-Perry Aggression Questionnaire (AQ-CV) and the Chinese version Morningness-Eveningness Questionnaire (MEQ-CV) were used to assess the aggressive behavior and chronotypes of the study subjects. The Kruskal-Wallis test was then used to compare the differences in aggression among adolescents with different chronotypes, and Spearman correlation analysis to determine the relationship between chronotypes and aggression. Further linear regression analysis was used to investigate the effects of chronotype, personality traits, family environment, and class environment on adolescent aggression.

RESULTS

There were significant differences in chronotypes between different age groups and different sexes. Spearman correlation analysis showed that the MEQ-CV total score was negatively correlated with the AQ-CV total score (r = -0.263) and score of each AQ-CV subscale. In Model 1, chronotypes were negatively associated with aggression when controlling for age and sex, and evening-type adolescents might be more likely to exhibit aggressive behavior (b = -0.513, 95% CI: [-0.712, -0.315], P < 0.001); in Model 2, the negative association remained after controlling for family and class environment on the basis of Model 1 (b = -0.404, 95% CI: [-0.601, -0.208], P < 0.001); and in Model 3, the negative association still existed after controlling for personality traits on the basis of Model 2 (b = -0.383, 95% CI: [-0.577, -0.190], P < 0.001).

CONCLUSION

Compared to morning-type adolescents, evening-type adolescents were more likely to exhibit aggressive behavior. Given social expectations for MT adolescents, adolescents should be actively guided to develop a good circadian rhythm that may be more conducive to their physical and mental development.

Association between sleep patterns, somatization, and depressive symptoms among Russian university students

In adolescents and young adults, physical and mental health are known to be associated with sleep. In this paper, we consider the connection between health indicators and sleep patterns. We collected and analyzed data of 267 master's and bachelor's degree students from 21 educational programs at one elite Russian university. Somatic health and mental health were measured using, respectively, the 8-item and the 15-item Patient Health Questionnaire, and sleep patterns were identified using the Munich Chronotype Questionnaire. The results indicated that shorter sleep time, later bedtime, and later rising time on workdays were associated with student somatic health. Shorter sleep on workdays was positively associated with the severity of depressive symptoms. Our findings highlight the importance of healthy sleep behavior for student health.

Predictor variables that affect the resilience of university students: The effect of chronotypes

AIM

The aim of this study was to investigate the effects of chronotypes and other variables as predictors of resilience in university students.

METHOD

The study was conducted with 1040 students studying at Ege University in Turkey.

RESULTS

The mean total Adult Resilience Scale (ARS) score of the students was found to be 120.23 ± 17.54 and the mean total score of the Morningness-Eveningness Questionnaire (MEQ) was 47.56 ± 8.95 and 63.0% of the students had intermediate type chronotype. It was determined that the variables explaining 21.9% of the ARS were the students' gender, school, income status, health assessment, and MEQ subtypes.

CONCLUSION

It was concluded that the students' resilience was above the average, that more than half of them had the intermediate type chronotype, and that the independent variables determined in the study partially explained their psychological resilience.

The hidden link between circadian entropy and mental health disorders

The high overlapping nature of various features across multiple mental health disorders suggests the existence of common psychopathology factor(s) (p-factors) that mediate similar phenotypic presentations across distinct but relatable disorders. In this perspective, we argue that circadian rhythm disruption (CRD) is a common underlying p-factor that bridges across mental health disorders within their age and sex contexts. We present and analyze evidence from the literature for the critical roles circadian rhythmicity plays in regulating mental, emotional, and behavioral functions throughout the lifespan. A review of the literature shows that coarse CRD, such as sleep disruption, is prevalent in all mental health disorders at the level of etiological and pathophysiological mechanisms and clinical phenotypical manifestations. Finally, we discuss the subtle interplay of CRD with sex in relation to these disorders across different stages of life. Our perspective highlights the need to shift investigations towards molecular levels, for instance, by using spatiotemporal circadian "omic" studies in animal models to identify the complex and causal relationships between CRD and mental health disorders.

Mediating Role of Psychological Maladjustment in Relation Between Dark Triad, Psychological Distress and Subjective Happiness of Pakistani Emerging Adults

The transition from adolescence to adulthood is fraught with challenges that might have impacts on later life and personality development. Earlier research investigated Dark Triad traits in connection to emotional problems. The current study, on the other hand, focused on investigating the mediating role of psychological maladjustment in the relation of Dark Triad traits, psychological distress, and subjective happiness in emerging adults. A sample of 546 participants aged 18–25 years (M = 21.2 years) from Pakistan have participated to complete an online survey. Standardized assessment tools were used to measure the targeted variables. Results indicated that Machiavellianism and psychopathy were positively associated with psychological distress, whereas narcissism appeared to be a non-significant predictor. Subjective happiness was positively associated with Machiavellianism and negatively associated with psychopathy. In addition, mediation analysis through Structural Equation Modeling (SEM) indicated that the Dark Triad traits (Machiavellianism and psychopathology), psychological distress, and subjective wellbeing were explained by psychological maladjustment. Implications and limitations are discussed.

Later Chronotype Correlates With Severe Depression in Indonesian College Students

Background and Objective The correlation between late chronotype and depression has been well documented, but reports from the equatorial area, where the sun shines throughout the year with less seasonal variation, are limited. In the present research study, we sought to 1) examine the relationship between the chronotype and mental health symptoms in an Indonesian student population and 2) explore the characteristics of those who lie at the extreme chronotype and psychometry.Methods This is a cross-sectional questionnaire-based study including undergraduate students in an Indonesian university (n = 493). We used the Munich Chronotype Questionnaires and the Depression, Anxiety, and Stress Scale to assess the chronotype and mental symptoms, respectively. Following this, a follow-up with an in-depth interview on the selected population at the extreme end of the chronotype was performed as an exploratory approach to identify their common characteristics.Results Among the tested parameters, the depression score was significantly associated with chronotype (p = 0.003), replicating previous findings from other areas with higher latitudes. The correlation persisted when males and females were analyzed separately (p = 0.008 and 0.037, respectively). A follow-up qualitative analysis revealed a potential subclinical, unrealized depression among the subjects; our findings revealed the use of smartphones during or before bedtime as a common factor among those with later chronotypes.Conclusions There is a correlation between depression score and chronotype among Indonesian college students, where subjects with later chronotype are more likely to have a higher depression score.

Greater preference for eveningness is associated with negative symptoms in an ultra-high risk for psychosis sample

AIM

Investigating biological processes in at-risk individuals may help elucidate the aetiological mechanisms underlying psychosis development, refine prediction models and improve intervention strategies. This study examined the associations between sleep disturbances, chronotype, depressive and psychotic symptoms in individuals at ultra-high risk for psychosis.

METHODS

A sample of 81 ultra-high risk patients completed clinical interviews and self-report assessments of chronotype and sleep during the Neurapro clinical trial. Mixed regression was used to investigate the cross-sectional associations between symptoms and sleep disturbances/chronotype.

RESULTS

Sleep disturbances were significantly associated with increased depressive and attenuated positive psychotic symptoms. Greater preference for eveningness was significantly associated with increased negative symptoms, but not with depressive or attenuated positive psychotic symptoms.

CONCLUSION

Sleep disturbances and chronotype may impact the emerging psychopathology experienced by ultra-high risk individuals. Further, the preliminary relationship observed between greater preference for eveningness and negative symptoms offers a unique opportunity to treat negative symptoms through chronobiological approaches.

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.

Mindful larks and lonely owls: The relationship between chronotype, mental health, sleep quality, and social support in young adults

Chronotype is related to mental health, with evening chronotypes being more susceptible to psychological disorders than intermediate and morning types. The present study investigated the relationship between chronotype, mental health, sleep quality, and social support in Canadian young adults. We surveyed 3160 university students aged 18-35 years. Participants completed the Morningness-Eveningness Questionnaire, the Hospital Anxiety and Depression Scale, the Mindful Attention Awareness Scale, the Pittsburgh Sleep Quality Index, and the Medical Outcomes Study - Social Support Survey. We conducted Bonferroni-corrected one-way analyses of covariance with post hoc paired comparisons to determine the relationship between the aforementioned variables, with age and sex as covariates. We further looked at the moderation of social support on the relationship between chronotype and sleep quality. Overall, 55%, 36% and 9% of participants were classified as intermediate, evening and morning types, respectively. There was a significant difference between chronotype on levels of depression, anxiety, and sleep quality, with evening types reporting more severe symptomology than morning-types and intermediate types. Morning types reported greater levels of overall social support and mindfulness. Evening types reported the lowest levels of all types of social support. Social support did not moderate the relationship between chronotype and sleep quality. This study further demonstrates the association between worse psychological well-being and eveningness and between more social support, and mindfulness in morning chronotype young adults. Education and intervention are warranted to help evening chronotypes manage the potential negative features of their circadian rhythm, as well as to cultivate a greater sense of social support and mindfulness.

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.

Linking RDoC and HiTOP: A new interface for advancing psychiatric nosology and neuroscience

The Research Domain Criteria (RDoC) and the Hierarchical Taxonomy of Psychopathology (HiTOP) represent major dimensional frameworks proposing two alternative approaches to accelerate progress in the way psychopathology is studied, classified, and treated. RDoC is a research framework rooted in neuroscience aiming to further the understanding of transdiagnostic biobehavioral systems underlying psychopathology and ultimately inform future classifications. HiTOP is a dimensional classification system, derived from the observed covariation among symptoms of psychopathology and maladaptive traits, which seeks to provide more informative research and treatment targets (i.e., dimensional constructs and clinical assessments) than traditional diagnostic categories. This article argues that the complementary strengths of RDoC and HiTOP can be leveraged in order to achieve their respective goals. RDoC's biobehavioral framework may help elucidate the underpinnings of the clinical dimensions included in HiTOP, whereas HiTOP may provide psychometrically robust clinical targets for RDoC-informed research. We present a comprehensive mapping between dimensions included in RDoC (constructs and subconstructs) and HiTOP (spectra and subfactors) based on narrative review of the empirical literature. The resulting RDoC-HiTOP interface sheds light on the biobehavioral correlates of clinical dimensions and provides a broad set of dimensional clinical targets for etiological and neuroscientific research. We conclude with future directions and practical recommendations for using this interface to advance clinical neuroscience and psychiatric nosology. Ultimately, we envision that this RDoC-HiTOP interface has the potential to inform the development of a unified, dimensional, and biobehaviorally-grounded psychiatric nosology.

Chronotype and social support among student athletes: impact on depressive symptoms

Previous studies have shown individuals with evening chronotype to have a greater likelihood for depression (self-reported and clinical ratings), especially in young adults. However, the mechanisms for this relationship remain unknown. Low levels of social support may be a plausible mechanism: young adults with evening chronotypes are awake when others are sleeping, which may lead to feelings of isolation or low support. This study examined links between chronotype, depression, and social support in relationship subtypes within a group of university student athletes. Data were obtained from 189 NCAA Division-I student athletes across all sports. Chronotype was assessed with the Circadian Energy Scale and ranged from -2 (definitely morning type) to +2 (definitely evening type). Depressive symptoms were assessed with Center for Epidemiological Studies Depression scale. Social support was assessed with the Multidimensional Scale of Perceived Social Support, which included subscales for Family, Friends, and Significant Other. A subscale for Team was created using the items from the Friends subscale (changing the word "friends" to "teammates"). Regression analyses adjusted for age, sex, and minority status. More evening chronotype was associated with higher reported depressive symptoms (p = .018), lower overall perceived social support (p = .001), and lower perceived social support specifically provided by family (p < .0001), friends (p < .0001), and teammates (p = .014). However, more evening chronotype was associated with higher depressive symptoms for higher, but not lower perceived social support from significant other. Moreover, chronotype-by-support interactions on depressive symptoms were observed; the statistical relationship between chronotype and depression was evident only in those with low (but not high) social support from friends and teammates. These data suggest that having a more evening chronotype may be associated with social isolation, and decreased opportunities for interactions with friends and teammates. This may contribute to the long-standing circadian association seen with depression in college student-athletes. Interventions aimed at increasing university support networks may reduce the impact of depression in students self-identifying with later chronotypes and sleep schedules.

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.

Depression and anxiety symptoms correlate with diurnal preference, sleep habits, and Per3 VNTR polymorphism (rs57875989) in a non-clinical sample

BACKGROUND

Evidences suggest that alterations in circadian rhythms trigger the development of mental disorders. Eveningness, sleep behavior, and circadian genes polymorphisms have been associated with depression and anxiety symptomatology. However, the mechanism underlying these interactions is not well understood. We investigated the contribution of diurnal preference, sleep habits, and PER3 VNTR polymorphism (rs57875989) to depression and anxiety symptoms in a Northeast sample from the Brazilian population.

METHODS

Eight hundred and four young adults completed the Morningness-Eveningness (MEQ), Munich Chronotype (MCTQ), Center for Epidemiologic Studies - Depression (CES-D), and Beck Anxiety Inventory (BAI) questionnaires. All participants were genotyped and linear regression was performed to test the interactions between the genetic /behavioral variants and depression/ anxiety symptoms.

RESULTS

Eveningness and sleep behaviors (bedtime, wake-up time, sleep duration, and midpoint of sleep) were correlated with depression symptomatology, specifically in somatic factors of the CES-D questionnaire. No correlation was found between diurnal preference/sleep habits with anxiety symptoms for both BAI total score and its factors. However, women with PER3^4/4 genotype showed less interpesonal affect in depression symptomatology and more anxiety symptoms in four factors of the BAI questionnaire.

LIMITATIONS

Mainly because this study was based on self-report questionnaires and was limited to undergraduate students aging 18 to 30 years old.

CONCLUSION

These results reinforce a role for sleep and diurnal preference in depression, and PER3 VNTR polymorphism in anxiety symptomatology, particularly in women.

Associations between diurnal preference, impulsivity and substance use in a young-adult student sample

A diurnal preference for eveningness is common in young adulthood and previous research has associated eveningness with anxiety symptoms as well as increased smoking and alcohol use behaviors. There is some evidence that impulsivity might be an important explanatory variable in these associations, but this has not been comprehensively researched. Here we used both subjective and objective measures of impulsivity to characterize impulsive tendencies in young adults and investigated whether trait impulsivity or trait anxiety could mediate the link between eveningness and substance use. A total of 191 university students (169 females), age range 18-25 y, completed the study. Diurnal preference, sleep quality, anxiety, impulsivity, and substance use were assessed by questionnaire. Impulsivity was also measured using a delay discounting task. Eveningness correlated with trait anxiety and trait impulsivity, and these associations were still significant after controlling for sleep quality. On the delayed discounting task, eveningness correlated with a tendency to prefer smaller immediate rewards over delayed, larger ones. Evening types also reported higher levels of alcohol and cigarette use even after controlling for sleep quality. These associations were found to be completely mediated by self-reported impulsivity; anxiety did not contribute. The current results could help inform interventions aiming to reduce substance use in young adult populations.

Angry night birds: Emotionality, activity and sociability temperament in adolescent chronotypes

There is growing interest in personality profiles associated with morningness-eveningness to foster an understanding of the behaviors and mental states of chronotypes. This study aimed to analyze the domains of emotionality, activity and sociability (EAS) temperament in relation to morningness-eveningness in adolescents. A sample of 539 school pupils aged 13-19 years completed the EAS Temperament Survey, the Composite Scale of Morningness and the Munich Chronotype Questionnaire. Amongst the five EAS domains (emotionality-distress, emotionality-fearfulness, emotionality-anger, activity and sociability), greater emotionality-anger was related to eveningness, while greater emotionality-distress was related to lower social jet lag. The results suggest that evening chronotypes can be temperamentally inclined to anger. The possible mechanisms of this association are discussed.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

ADHD 24/7: Circadian clock genes, chronotherapy and sleep/wake cycle insufficiencies in ADHD

Objectives: The current paper addresses the evidence for circadian clock characteristics associated with attention-deficit hyperactivity disorder (ADHD), and possible therapeutic approaches based on chronomodulation through bright light (BL) therapy.Methods: We review the data reported in ADHD on genetic risk factors for phase-delayed circadian rhythms and on the role of photic input in circadian re-alignment.Results: Single nucleotide polymorphisms in circadian genes were recently associated with core ADHD symptoms, increased evening-orientation and frequent sleep problems. Additionally, alterations in exposure and response to photic input may underlie circadian problems in ADHD. BL therapy was shown to be effective for re-alignment of circadian physiology toward morningness, reducing sleep disturbances and bringing overall improvement in ADHD symptoms. The susceptibility of the circadian system to phase shift by timed BL exposure may have broad cost-effective potential implications for the treatment of ADHD.Conclusions: We conclude that further research of circadian function in ADHD should focus on detection of genetic markers (e.g., using human skin fibroblasts) and development of BL-based therapeutic interventions.

Time of Day Matters: An Exploratory Assessment of Chronotype in a Forensic Psychiatric Hospital

A growing body of evidence links the late chronotype to mental illness, aggression, and aversive personality traits. However, much of what we know about these associations is based on healthy cohorts, and it is unclear how individuals with high levels of aggression, including forensic psychiatric populations, but not offenders, are affected. The present study aimed to measure chronotype in a forensic psychiatric inpatient population, evaluate the impact of diagnosis, and identify any interactive relationships between chronotype, diagnosis, aggression, and dark triad traits. Subjects completed the reduced Morningness-Eveningness Questionnaire (rMEQ), Munich ChronoType Questionnaire (MCTQ), Pittsburgh Sleep Quality Index (PSQI), Buss Perry Aggression Questionnaire-Short Form (BPAQ-SF), and Short Dark Triad Questionnaire (SD3). We sampled 55 forensic psychiatric patients (52 males) between the ages of 23 and 73 years (mean ± SD: 39.6 ± 14.3 years). Among the patients sampled, 25% were evening types and 36% were morning types. Eveningness was greater in patients with a personality disorder; however, no chronotype differences were found for psychosis patients. Patients without psychosis had a positive association between anger and eveningness, as well as between hostility and eveningness. For subjects with a substance use disorder, morningness was positively associated with narcissism. Conversely, an association between eveningness and greater narcissism was identified in patients who did not have a substance use disorder. These findings suggest that, compared to the general population, evening types are more prevalent in forensic psychiatric populations, with the strongest preference among patients diagnosed with a personality disorder. No differences in chronotype were identified for psychosis patients, which may be related to anti-psychotic medication dosing. Given the sex distribution of the sample, these findings may be more relevant to male populations.

Psychopathy and chronotype disposition: the mediating role of depression

This study examined the relationship between dark triad personality traits and chronotype disposition, whilst incorporating the mediating role of anxiety and/or depression after excluding individuals presenting insomnia and/or physiological sleep-disorder symptoms. Members of the general population (N = 453) completed online measures of dark triad personality traits, chronotype, and anxious and depressive symptoms. Psychopathy and Machiavellianism were independently related to an evening chronotype disposition. However, after accounting for age, sex, anxiety and depression, psychopathy and depression remained the only significant predictors of chronotype. Therefore, whilst psychopathy was the strongest predictor of an evening chronotype preference, this relationship is partially mediated by depression. Individuals presenting an evening disposition may display increased psychopathic traits due to greater emotion dysregulation. This is potentially perpetuated by depressive symptoms stemming from a delayed or blunted affective rhythm. Interacting factors (e.g. reduced light exposure) may also contribute to alterations in the biological rhythm amongst evening-types, resulting in a negative feedback cycle. Targeting chronotype and depressive symptoms amongst individuals presenting psychopathic tendencies could increase the efficacy of existing sleep-based interventions for hostile behaviour.

Chronotypes and its association with psychological morbidity and childhood parasomnias

BACKGROUND

The relationship between chronotypes and sleeping problems is not clear. The objective of the study was to identify the relative occurrence of chronotypes among college students and to explore adult psychological morbidity and childhood sleeping problems across chronotypes.

MATERIALS AND METHODS

One hundred and fifty undergraduate medical students were assigned into different chronotypes by Morningness-Eveningness Questionnaire and they were further assessed using Self-Reporting Questionnaire, Parasomnia Questionnaire (adapted from the Adult Sleep Disorders Questionnaire), and Pittsburgh Sleep Quality Index.

RESULTS

Intermediate chronotype was the most common, seen in 87 (58%) students, followed by evening type in 34 (22.7%). Evening types have more difficulties in making a decision, becoming exhausted more easily and feeling worthless than other chronotypes. Evening-oriented students showed a significantly higher frequency of initial insomnia and poorer overall sleep quality than the other groups. The current bedwetting was more in evening types; there was no difference in any other current and childhood parasomnias.

CONCLUSIONS

Evening chronotypes had greater difficulty in decision-making, and they were more vulnerable to feel worthless. No significant association was found between childhood parasomnias and chronotypes except persistent bedwetting during adulthood in evening types.

Der Zusammenhang zwischen Schlafproblemen, unzureichender Schlafdauer und psychischen Auffälligkeiten bei Kindern und Jugendlichen

Zusammenfassung. Schlafprobleme und eine unzureichende Schlafdauer können die psychische Gesundheit im Kindes- und Jugendalter nachhaltig beeinträchtigen. Daten von 6.670 Jungen und Mädchen im Alter von 11 – 13 und 14 – 17 Jahren, aus dem Kinder- und Jugendgesundheitssurvey (KIGGS), wurden getrennt nach Geschlechtern analysiert, um zu untersuchen, ob Schlafprobleme und eine unzureichende Schlafdauer mit einer höheren Risikowahrscheinlichkeit für psychische Auffälligkeiten einhergehen. Während Schlafprobleme unabhängig von Geschlecht und Alter mit einem höheren Risiko für alle Symptombereiche (OR = 1.52 – 3.49) verbunden sind, findet sich hinsichtlich einer geringen Schlafdauer nur bei Mädchen eine höheres Risikowahrscheinlichkeit für Auffälligkeiten im externalisierenden und internalisierenden Bereich. Damit scheint sich der Zusammenhang zwischen unzureichender Schlafdauer und psychischen Auffälligkeiten bei Jungen und Mädchen zu unterscheiden. Mögliche Ursachen und Implikationen für die pädiatrische und psychiatrische Praxis werden diskutiert.

Sleep and circadian risk factors for alcohol problems: a brief overview and proposed mechanisms

Disturbances in sleep and circadian rhythms may be important, albeit underappreciated, risk factors for the initiation of alcohol use and the escalation of alcohol problems. In this review, we first describe sleep and circadian changes during adolescence and young adulthood. Second, we explain how these sleep/circadian changes intersect with onset and escalation of alcohol use. Third, we briefly note how alcohol use (whether acute or chronic) affects sleep and circadian rhythms. Finally, we articulate a conceptual model containing two mechanistic pathways-broadly positive and negative reinforcement-linking sleep/circadian factors to alcohol involvement before listing key areas we believe are ripe for further inquiry.

Subclinical Scores in Self-Report Based Screening Tools for Attention Deficits Correlate With Cognitive Traits in Typical Evening-Type Adults Tested in the Morning

Previous studies suggest that in adolescents and young adults, evening chronotype is a subclinical factor in physical, cognitive, and psychiatric fitness; poor sleep habits and larger misalignment with the social schedule constraints may exacerbate symptoms of inattention, impulsivity and the risks for detrimental behaviors. The influence of chronotype on neurocognitive performance during morning hours and scores in self-reports about attention deficit symptoms (ADS) and executive functioning, was explored in 42 healthy young university students (29 women), divided to evening type (ET) and combined morning/intermediate type (MT/IT) groups. Evening chronotypes scored significantly higher in the questionnaires of inattention Adult ADHD Self-Report Scale (ASRS-6) (MT/IT: 1.62 ± 1.59; ET: 2.71 ± 1.62, p < 0.05) and day-time sleepiness Epworth scale (MT/IT: 7.19 ± 5.17; ET: 11.48 ± 5.26, p < 0.01), reported lower subjective alertness (MT/IT: 63.02 ± 21.40; ET: 40.76 ± 17.43, p < 0.001), and had slower reaction times (MT/IT: 321.47 ± 76.81; ET: 358.94 ± 75.16, p < 0.05) during tests, compared to non-evening chronotypes. Nevertheless, ETs did not significantly differ in self-reports of executive functioning in the Behavioral Rating Inventory of Executive Functions-A (BRIEF-A) from non-ETs. The scores on standard self-report screening tools for ADS and executive functioning (ASRS-6, BRIEF-A-Metacognition) correlated with eveningness. We conclude that eveningness, subjective sleepiness and low arousal levels during morning can present as subclinical Attention Deficit and Hyperactivity Disorder (ADHD) symptoms in typical young adults with no evident sleep problems. Self-report based screening tools for ADS and executive functioning reflect chronotype-related traits in healthy young adults. Strong eveningness may bias the results of neurocognitive performance screening for ADHD when administered at morning hours.

Preliminary Evidence That Real World Sleep Timing and Duration are Associated With Laboratory-Assessed Alcohol Response

BACKGROUND

Sleep timing and evening chronotype have been implicated in alcohol use problems but research has yet to study them in relation to theory-driven laboratory-based measures of alcohol use disorder risk. The current study examined (i) whether chronotype, sleep timing, and/or sleep duration are associated with alcohol response (subjective stimulation, sedation, and behavioral disinhibition) and (ii) if sex and race moderate these associations.

METHODS

Adult drinkers (N = 144; 46 female participants) completed 2 counterbalanced beverage administration sessions (alcohol and nonalcohol) during which they rated stimulation/sedation and completed a cued go/no-go task. They reported bed and waketimes over 10 days.

RESULTS

Later sleep timing was associated with greater increases in alcohol stimulation, but among male and White participants only. Later sleep timing (among male participants) and greater eveningness (examined among White male participants only) were associated with greater overall stimulation on average in the alcohol session relative to the nonalcohol session, irrespective of alcohol consumption. More variable sleep duration was associated with greater increases in sedation.

CONCLUSIONS

These findings offer preliminary, but novel evidence that sleep characteristics may relate to the relative stimulating and sedating effects of alcohol, thereby influencing the risk for alcohol problems.

Internalizing symptoms and chronotype in youth: A longitudinal assessment of anxiety, depression and tripartite model

Biological rhythm theories highlight the reciprocal relations between dysregulated circadian patterns and internalizing psychopathology. Chronotype characterizes individuals' diurnal preference, as some exhibit more morningness or eveningness. Previous research suggests that eveningness prospectively predicts depression in adolescence. Anxiety often co-occurs with depression, but little is known about longitudinal, reciprocal associations between chronotype and anxiety, and whether this relationship remains after controlling for depression. We assessed different forms of anxiety (social, panic, separation), positive/negative affect, anxious arousal (from tripartite theory), and depression, in relation to chronotype to better understand the specificity and directionality of associations between chronotype and internalizing problems in adolescence. Community youth participated in three assessment time points: T1, T2 (18-months post-T1), and T3 (30-months post-T1) as part of a larger longitudinal study. Youth completed self-report measures of anxiety, depression, positive and negative affect, and chronotype. Regression analyses showed that eveningness: (1) concurrently associated with decreased separation anxiety, elevated symptoms of depression and low levels of positive affect, (2) was prospectively predicted by elevated depression, (3) did not predict later symptoms of anxiety. The reciprocal, prospective relationship between chronotype and internalizing psychopathology is specific to depression during adolescence.

Time to think: Subjective sleep quality, trait anxiety and university start time

Poor quality sleep is related to mental health and there is increasing interest in student wellbeing and mental health. The aim of the current study was to evaluate sleep quality, daytime dozing, anxiety proneness, chronotype and preferred start time in a sample of university students. A total of 546 university students (age range, 18-55) from two university located in South East England were included and completed an online survey. Participants' self-reported age, gender, year and field of study. Sleep quality, anxiety, daytime dozing, coffee/caffeine/tobacco use (coded as binary variables), preferred start time and chronotype were also recorded. Data were analysed using independent samples t-tests, chi-square, simple mediation-analyses and Analysis of Variance. Across the entire sample 46% percent of participants rated their sleep as fairly bad or very bad. Poor quality sleep was associated with significantly higher levels of anxiety which was not mediated by chronotype. Poor quality sleep is more prevalent in the first year of university and our sample endorsed a start time for university activities approximately 2 h later than currently timetabled. The current findings demonstrate that a large proportion of students are chronically sleep deprived, obtaining, on average, less than 7 h sleep per night on week days and this was more marked in first year students. In addition, we show that poor sleep is associated with increased anxiety. Based on the current evidence the authors suggest a review of current university timetabling and examination scheduling merits immediate consideration by policy makers and educators.

Making Memories: Why Time Matters

In the last decade advances in human neuroscience have identified the critical importance of time in creating long-term memories. Circadian neuroscience has established biological time functions via cellular clocks regulated by photosensitive retinal ganglion cells and the suprachiasmatic nuclei. Individuals have different circadian clocks depending on their chronotypes that vary with genetic, age, and sex. In contrast, social time is determined by time zones, daylight savings time, and education and employment hours. Social time and circadian time differences can lead to circadian desynchronization, sleep deprivation, health problems, and poor cognitive performance. Synchronizing social time to circadian biology leads to better health and learning, as demonstrated in adolescent education. In-day making memories of complex bodies of structured information in education is organized in social time and uses many different learning techniques. Research in the neuroscience of long-term memory (LTM) has demonstrated in-day time spaced learning patterns of three repetitions of information separated by two rest periods are effective in making memories in mammals and humans. This time pattern is based on the intracellular processes required in synaptic plasticity. Circadian desynchronization, sleep deprivation, and memory consolidation in sleep are less well-understood, though there has been considerable progress in neuroscience research in the last decade. The interplay of circadian, in-day and sleep neuroscience research are creating an understanding of making memories in the first 24-h that has already led to interventions that can improve health and learning.

Sex Differences in Photic Entrainment and Sensitivity to Ethanol-Induced Chronodisruption in Adult Mice After Adolescent Intermittent Ethanol Exposure

BACKGROUND

Evidence supports a role for the circadian system in alcohol use disorders, but the impact of adolescent alcohol exposure on circadian timing later in life is unknown. Acute ethanol (EtOH) attenuates circadian photic phase-resetting in adult, but not adolescent, rodents. However, nearly all studies have focused on males and it is unknown whether this adolescent-typical insensitivity to EtOH persists into adulthood after adolescent drinking.

METHODS

Circadian activity was monitored in C57BL/6J mice receiving adolescent intermittent EtOH (AIE) exposure (15% EtOH and water every other day throughout adolescence) or water alone followed by 24 days wherein EtOH was not available (washout). Mice then received a challenge dose of EtOH (1.5 g/kg, intraperitoneal) or saline 15 minutes prior to a 30-minute phase-delaying light pulse and then were released into constant darkness (DD). To control for possible phase-shifting by EtOH challenge alone, a separate group of mice underwent AIE exposure (or water-only) and washout and then received an EtOH or saline injection, but did not receive a light pulse prior to DD.

RESULTS

Striking sex differences in nearly all measures of circadian photic entrainment were observed during adolescence but AIE effects were subtle and few. Only EtOH-naïve adult male mice showed attenuated photic phase-shifts with EtOH challenge, while all other groups showed normal phase-resetting responses to light. AIE-exposed females showed a persistent delay in activity offset.

CONCLUSIONS

Adult male AIE-exposed mice retained adolescent-like insensitivity to EtOH-induced suppression of photic phase-resetting, suggesting AIE-induced "lock-in" of an adolescent behavioral phenotype. Adult AIE-exposed females showed delayed initiation of the rest phase. Our results also indicate that intermittent EtOH drinking has subtle effects on circadian activity in mice during adolescence that differ from previously reported effects on adult males. The observed sex differences in circadian activity, EtOH consumption and preference, and responses to EtOH challenge merit future mechanistic study.

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.

Association between the Munich Chronotype Questionnaire and Wrist Actigraphy

Chronotype refers to individuals' preferences for timing of sleep and wakefulness. It can be quantified by measuring the midpoint time between the start and end of sleep during free days. Measuring chronotype is helpful to diagnose circadian rhythm sleep-wake disorders. The Munich Chronotype Questionnaire (MCTQ) is a self-reported measure of chronotype that calculates the midpoint of sleep on free days based on self-reported bed and wake times. Self-reports of sleep are prone to bias. The objective was to examine the agreement between the MCTQ-derived midpoint and an objective measure obtained using wrist actigraphy. The sleep of 115 participants aged 18–34 (mean = 24, SD = 4.6) was monitored with actigraphy for 4 to 6 consecutive nights. The corrected midpoint of sleep on free days was derived from sleep start and end times on both free days and scheduled days. The corrected midpoint of sleep on free days as measured by the MCTQ was 4:56 (SD = 1 : 16) and by actigraphy was 4:51 (SD = 1 : 23). They were not significantly different (t₍₈₇₎ = 0.66, p = 0.51). A strong correlation was found between these two measurements (r₍₈₈₎ = 0.73, p < 0.001). The 95% limits of agreement were between −1:37:19 and 2:14:38. MCTQ and actigraphy provide similar results for the corrected midpoint of sleep on free days.

Eveningness chronotype, insomnia symptoms, and emotional and behavioural problems in adolescents

OBJECTIVE

Eveningness tendency and insomnia are common in adolescents, but whether they have an independent or synergistic effect on the risk of psychopathology have remained undefined. The present study aimed to examine eveningness chronotype and insomnia symptoms in relation to mental health and emotional and behavioural problems in a community-based adolescent population.

METHODS

A total of 4948 adolescents (weighted mean age: 14.5 ± 1.8 years, weighted percentage of females: 48.9%) completed the measures. Insomnia was assessed by the Insomnia Severity Index (ISI), and chronotype preference was measured by the reduced version of the Morningness-Eveningness Questionnaire (MEQ). Emotional and behavioural problems and mental health were assessed by the Strengths and Difficulties Questionnaire (SDQ) and the General Health Questionnaire (GHQ-12), respectively. Potential confounders including demographic factors, pubertal status, general health, and sleep duration were controlled for in the analyses.

RESULTS

Insomnia symptoms were prevalent in evening-type adolescents (52% vs intermediate-type: 34.3%, morning-type: 18.0%, p < 0.001), especially two subtypes of insomnia symptoms, including difficulty initiating sleep and difficulty maintaining sleep. Eveningness and insomnia were independently associated with an increased risk of having emotional and behavioural problems (eveningness: adjusted odds ratio [AdjOR] = 1.88, 95% confidence interval [CI] = 1.61-2.19, p < 0.001; insomnia: AdjOR = 3.66, 95% CI = 2.73-4.91) as well as poor mental health in adolescents (eveningness: AdjOR = 1.25, 95% CI = 1.04-1.52, p < 0.001; insomnia: AdjOR = 3.63, 95% CI = 2.41-5.03).

CONCLUSIONS

Eveningness and insomnia symptoms are independently associated with the risk of psychopathology in adolescents. Our findings underscore the need to address both sleep and circadian factors in assessing and managing emotional and behavioural problems in the adolescent population.

Association of possible sleep bruxism in children with different chronotype profiles and sleep characteristics

Sleep bruxism (SB) in children has been associated with several sleep characteristics, which may alter their sleep pattern. This change affects the internal biological clock and consequently the chronotype profile. The aim of this study was to evaluate the existence of an association between possible SB in children with specific chronotype profiles and sleep characteristics. The study included 207 parents/guardians of children aged between 3 and 12 years who were waiting for their children's dental treatment at the Pediatric Dentistry Clinic of the Federal University of Rio de Janeiro, Brazil. A questionnaire on the socio-demographic characteristics of parents and children as well as on the features of the children's sleep was applied. In addition, the CIRENS scale (Circadian Energy Scale) was completed by the parents to identify the children's chronotype. A chi-squared test was used to determine the association between possible SB, the chronotype, and sleep characteristics. A multiple logistic regression model was implemented to observe the influence of chronotype, age, and other independent variables on the possible SB. The logistic regression model demonstrated that nocturnal agitation (p = 0.009; OR = 3.42) and nightmares (p = 0.045; OR = 3.24) were associated with possible SB in children. Although no significant association (p = 0 .089) between the chronotype profile and possible SB was observed in the 3 to 5 years age group, a proportional difference was observed between the chronotype categories in this age group-12.5% of children with SB had a morning type, while 26.4% had an intermediate type and 47.8% an evening type compared to those without possible SB. Nocturnal agitation and nightmares were associated with possible SB. In addition, young children with an evening chronotype had a tendency toward possible SB.

Circadian Clock Model Supports Molecular Link Between PER3 and Human Anxiety

Generalized anxiety and major depression have become increasingly common in the United States, affecting 18.6 percent of the adult population. Mood disorders can be debilitating, and are often correlated with poor general health, life dissatisfaction, and the need for disability benefits due to inability to work. Recent evidence suggests that some mood disorders have a circadian component, and disruptions in circadian rhythms may even trigger the development of these disorders. However, the molecular mechanisms of this interaction are not well understood. Polymorphisms in a circadian clock-related gene, PER3, are associated with behavioral phenotypes (extreme diurnal preference in arousal and activity) and sleep/mood disorders, including seasonal affective disorder (SAD). Here we show that two PER3 mutations, a variable number tandem repeat (VNTR) allele and a single-nucleotide polymorphism (SNP), are associated with diurnal preference and higher Trait-Anxiety scores, supporting a role for PER3 in mood modulation. In addition, we explore a potential mechanism for how PER3 influences mood by utilizing a comprehensive circadian clock model that accurately predicts the changes in circadian period evident in knock-out phenotypes and individuals with PER3-related clock 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.

Associations between chronotypes and psychological vulnerability factors of depression

Chronotypes have been associated with psychopathology. The eveningness chronotype has been consistently linked with depressed states or depressive disorder, but the underlying mechanism remains unclear. Prior studies have shown associations between chronotype and personality traits that are linked to depression (e.g. neuroticism), but other psychological vulnerability factors have not been previously investigated in relation to chronotypes. The aim of this study was to examine the association between chronotypes, depression and psychological risk factors of depression (namely, cognitive reactivity and worry), in a large cohort of depressed patients and healthy individuals. We used data from the Netherlands Study of Depression and Anxiety (n = 1654), which includes 1227 clinically diagnosed individuals with a lifetime diagnosis of depression and 427 healthy controls. We assessed cognitive reactivity (Leiden Index of Depression Sensitivity-Revised) and trait worry (Penn State Worry Questionnaire). We controlled for sociodemographic factors as well as for insomnia and neuroticism. We found that the evening type is associated with higher cognitive reactivity scores, especially with increased rumination. Cognitive reactivity also mediated the relationship between chronotype and depression status, even when controlling for neuroticism and insomnia. Trait worry was not associated with chronotype. Our findings show that depressogenic cognitions are more prevalent in evening types and perhaps mediate the association between chronotype and depression. Further prospective research is needed to determine the timeline of the association. Nevertheless, results imply that targeting depressogenic cognitive processes, perhaps in combination with chronotherapeutic treatments, may be particularly useful in evening types.