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

Relationship of Sleep Disorder with Neurodegenerative and Psychiatric Diseases: An Updated Review

Sleep disorders affect many people worldwide and can accompany neurodegenerative and psychiatric diseases. Sleep may be altered before the clinical manifestations of some of these diseases appear. Moreover, some sleep disorders affect the physiological organization and function of the brain by influencing gene expression, accelerating the accumulation of abnormal proteins, interfering with the clearance of abnormal proteins, or altering the levels of related hormones and neurotransmitters, which can cause or may be associated with the development of neurodegenerative and psychiatric diseases. However, the detailed mechanisms of these effects are unclear. This review mainly focuses on the relationship between and mechanisms of action of sleep in Alzheimer's disease, depression, and anxiety, as well as the relationships between sleep and Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. This summary of current research hotspots may provide researchers with better clues and ideas to develop treatment solutions for neurodegenerative and psychiatric diseases associated with sleep disorders.

Crime Risk and Depression Differentially Relate to Aspects of Sleep in Patients with Major Depression or Social Anxiety

Individuals with internalizing conditions such as depression or anxiety are at risk of sleep difficulties. Social-ecological models of sleep health propose factors at the individual (e.g., mental health) and neighborhood (e.g., crime risk) levels that contribute to sleep difficulties. However, these relationships have been under-researched in terms of internalizing conditions. Therefore, the current study comprised participants diagnosed with major depression (n = 24) or social anxiety (n = 35). Sleep measures included actigraphic variables (i.e., total sleep time, waking after sleep onset, sleep onset latency) and subjective sleep quality. Geocoding was used to assess nationally-normed crime risk exposure at the person level (e.g., murder, assault) and property level (e.g., robbery, burglary). Analyses consisted of independent t-tests to evaluate potential differences between diagnostic groups. To examine relationships, multiple regressions were used with internalizing symptoms, crime risk, and age as independent variables and sleep measures as the dependent variable. The t-test results revealed that groups differed in symptoms and age but not sleep or neighborhood crime. Regression results revealed crime risk positively corresponded with sleep onset latency but no other sleep measures. Also, only depression positively corresponded with total sleep time. Preliminary findings suggest exposure to crime and depression relate differentially to facets of sleep in individuals with internalizing conditions.

Association between chronic diseases and depression in the middle-aged and older adult Chinese population-a seven-year follow-up study based on CHARLS

Background

With the aging of the Chinese population, the prevalence of depression and chronic diseases is continually growing among middle-aged and older adult people. This study aimed to investigate the association between chronic diseases and depression in this population.

Methods

Data from the China Health and Retirement Longitudinal Study (CHARLS) 2011-2018 longitudinal survey, a 7-years follow-up of 7,163 participants over 45 years old, with no depression at baseline (2011). The chronic disease status in our study was based on the self-report of the participants, and depression was defined by the 10-item Center for Epidemiologic Studies Depression Scale (CES-D-10). The relationship between baseline chronic disease and depression was assessed by the Kaplan-Meier method and Cox proportional hazards regression models.

Results

After 7-years follow-up, 41.2% (2,951/7163, 95% CI:40.1, 42.3%) of the participants reported depression. The analysis showed that participants with chronic diseases at baseline had a higher risk of depression and that such risk increased significantly with the number of chronic diseases suffered (1 chronic disease: HR = 1.197; 2 chronic diseases: HR = 1.310; 3 and more chronic diseases: HR = 1.397). Diabetes or high blood sugar (HR = 1.185), kidney disease (HR = 1.252), stomach or other digestive diseases (HR = 1.128), and arthritis or rheumatism (HR = 1.221) all significantly increased the risk of depression in middle-aged and older adult Chinese.

Conclusion

The present study found that suffering from different degrees of chronic diseases increased the risk of depression in middle-aged and older adult people, and these findings may benefit preventing depression and improving the quality of mental health in this group.

The association between various dimensions of sleep parameters and mental health: A large cross-sectional study of 13554 Chinese students

OBJECTIVES

We aimed to investigate the association between multiple sleep variables and mental health among Chinese students aged 9-22.

METHOD

We stratified the included 13,554 students by educational levels. Sleep parameters contained sleep duration on school days and weekends, napping time, chronotype and social jetlag (SJL), which were calculated via questionnaires. Individual psychological well-being and distress were assessed by Warwick-Edinburgh mental Well-being scale and the Kessler Psychological Distress Scale 10 respectively. The multiple linear and binary logistic regression were applied to analyze the association of sleep with mental health.

RESULTS

Short sleep on school days showed significantly positive association with psychological problems. While among senior high school students, we found reverse result that sleeping less might negatively associated with more severe distress (7-8 h: aOR = 0.67, 95% CI: 0.46, 0.97). The association of sleep duration with mental health was attenuated a lot on weekends. The chronotype was significantly related with mental health in primary and junior high school: intermediate chronotype (vs late chronotype) was associated with greater wellbeing (β = 1.03, 95% CI: 0.09, 1.96; β = 1.89, 95% CI: 0.81, 2.97) and less distress (aOR = 0.78, 95% CI: 0.60, 1.00; aOR = 0.73, 95% CI: 0.58, 0.91). The relationship between SJL, napping duration and psychological health problems were also observed in some educational levels.

CONCLUSION

Sleep deprivation on school days, late chronotype and SJL were positively associated with worse mental health in our study, which differed among various educational stages.

Association between parental control and depressive symptoms among college freshmen in China: The chain mediating role of chronotype and sleep quality

BACKGROUND

College freshmen tend to have more psychological and behavioral problems compared with other populations, especially depressive symptoms. Perceived parental control has been proved to play a significant role in mental health among children and adolescents. Based on the theoretical and empirical research of chronotype and sleep quality, this study constructed a chain mediating model to examine whether they mediated the relationship between parental control and depressive symptoms among Chinese college freshmen.

METHODS

A total of 2014 college freshmen from Dali University were recruited to participate in this study and completed self-report Parental Bonding Instrument (PBI), Morningness-Eveningness Questionnaire (MEQ), Pittsburgh Sleep Quality Index (PSQI) and Self-Rating Depression Scale (SDS). PROCESS 3.5 for SPSS was applied to determine the chain mediating effect of chronotype and sleep quality between parental control and depressive symptoms.

RESULTS

College freshmen with depressive symptoms have higher levels of parental control and worse subjective sleep quality than normal population (all p < 0.001). All study variables are correlated with each other, while chronotype has no significant association with depressive symptoms (r = -0.03, p > 0.05). Both maternal and paternal control have a direct link with depressive symptoms (β = 0.86, p < 0.001; β = 0.88, p < 0.001). Parental control could affect depressive symptoms via the independent mediating effect of sleep quality and the chain mediating effect of chronotype and sleep quality. The total indirect effects of maternal and paternal control on depressive symptoms are 0.93 and 0.94, respectively.

CONCLUSIONS

Chronotype and sleep quality could mediate the association between parental control and depressive symptoms.

Association between trajectories of problematic mobile phone use and chronotype among Chinese college students

AIMS

This study aimed to describe the prevalence of problematic mobile phone use (PMPU) and chronotype among Chinese college students, estimate PMPU development trajectories, and further examine the effect of PMPU trajectories on chronotype.

DESIGN

In a stratified cluster sampling design, PMPU and chronotype were evaluated in 999 college students from two universities in a 2-year prospective investigation from April 2019 to April 2021, and an investigation was conducted every six months (time 1 ∼ time 5, T1 ∼ T5).

PARTICIPANTS

N = 999 college students (mean age at T1: 18.8 years (SD = 1.2), 37.7% male) took part in the study.

MEASUREMENTS

The Self-rating Questionnaire for Adolescent Problematic Mobile Phone Use (SQAPMPU) and the Pittsburgh Sleep Quality Index (PSQI) were used to assess the PMPU and sleep quality of college students at each time point. The Morning and Evening Questionnaire (MEQ) was adopted to investigate the chronotype of college students at T5.

FINDINGS

The prevalence of PMPU at T1 ∼ T5 was 24.3%, 27.3%, 35.1%, 31.2% and 31.9%, respectively. The prevalence rates of morning types (M-types), neutral types (N-types), and evening types (E-types) were 19.1%, 70.8%, and 10.1%, respectively. Using latent growth mixture modelling, we identified three trajectories of PMPU: low-level (49.5%), moderate-level (38.6%), and high-level score trajectories (11.9%). Multivariate logistic regression analysis results showed that a trajectory with a high score was positively associated with E-types (P < 0.05). After stratification by gender, a high-level score trajectory was positively associated with E-types only among female college students (P < 0.05). There were sex differences in the association between trajectories of PMPU and chronotype.

CONCLUSION

Long-term symptoms of PMPU may be a potential risk factor for circadian rhythm disturbance among college students, and this effect was significantly different between genders.

Human circadian rhythm studies: Practical guidelines for inclusion/exclusion criteria and protocol

As interest in circadian rhythms and their effects continues to grow, there is an increasing need to perform circadian studies in humans. Although the constant routine is the gold standard for these studies, there are advantages to performing more naturalistic studies. Here, a review of protocols for such studies is provided along with sample inclusion and exclusion criteria. Sleep routines, drug use, shift work, and menstrual cycle are addressed as screening considerations. Regarding protocol, best practices for measuring melatonin, including light settings, posture, exercise, and dietary habits are described. The inclusion/exclusion recommendations and protocol guidelines are intended to reduce confounding variables in studies that do not involve the constant routine. Given practical limitations, a range of recommendations is provided from stringent to lenient. The scientific rationale behind these recommendations is discussed. However, where the science is equivocal, recommendations are based on empirical decisions made in previous studies. While not all of the recommendations listed may be practical in all research settings and with limited potential participants, the goal is to allow investigators to make well informed decisions about their screening procedures and protocol techniques and to improve rigor and reproducibility, in line with the objectives of the National Institutes of Health.

The fall of vulnerability to sleep disturbances in evening chronotypes when working from home and its implications for depression

Eveningness is distinctively associated with sleep disturbances and depression symptoms due to the misalignment between biological and social clocks. The widespread imposition of remote working due to the COVID-19 pandemic allowed a more flexible sleep schedule. This scenario could promote sleep and mental health in evening-type subjects. We investigated the effect of working from home on sleep quality/quantity and insomnia symptoms within the morningness-eveningness continuum, and its indirect repercussions on depressive symptomatology. A total of 610 Italian office workers (mean age ± standard deviation, 35.47 ± 10.17 years) and 265 remote workers (40.31 ± 10.69 years) participated in a web-based survey during the second contagion wave of COVID-19 (28 November–11 December 2020). We evaluated chronotype, sleep quality/duration, insomnia, and depression symptoms through validated questionnaires. Three moderated mediation models were performed on cross-sectional data, testing the mediation effect of sleep variables on the association between morningness-eveningness continuum and depression symptoms, with working modality (office vs. remote working) as moderator of the relationship between chronotype and sleep variables. Remote working was associated with delayed bedtime and get-up time. Working modality moderated the chronotype effect on sleep variables, as eveningness was related to worse sleep disturbances and shorter sleep duration among the office workers only. Working modality also moderated the mediation of sleep variables between chronotype and depression. The above mediation vanished among remote workers. The present study suggests that evening-type people did not show their characteristic vulnerability to sleep problems when working from home. This result could imply a reduction of the proposed sleep-driven predisposition to depression of late chronotypes. A working environment complying with individual circadian preferences might ensure an adequate sleep quantity/quality for the evening-type population, promoting their mental health.

The mediating effect of attachment insecurity on circadian consequences of childhood trauma

Circadian preferences have been associated with mental health as well as social and physical health in recent years. However, factors associated with circadian preferences have not been fully elucidated. The main aim of this study is to investigate the associations of childhood trauma and attachment styles with circadian preferences. A total of 673 participants were evaluated using the Morningness-Eveningness Questionnaire (MEQ), the Childhood Trauma Questionnaire 28 (CTQ-28), and the Experiences in Close Relationships-Revised (ECR-R) questionnaire. The results indicated that 14.9% (n = 100) of the participants were morning type, 20.6% (n = 139) were evening type, and 64.5% (n = 434) were intermediate type. Both childhood trauma and attachment-related anxiety/avoidance scores were associated with being evening type (p < .01). Moreover, attachment-related anxiety and avoidance fully mediated the association between childhood trauma and circadian preferences. The present study showed that attachment styles might be associated with circadian preferences. Further studies are needed to replicate these results and to infer explanatory mechanisms for these cross-sectional associations.

Stress Susceptibility Moderates the Relationship Between Eveningness Preference and Poor Sleep Quality in Non-Acute Mood Disorder Patients and Healthy Controls

OBJECTIVE

This study aimed to investigate the relationship between eveningness preference and poor sleep quality and eventually examine the moderation effect of stress susceptibility.

METHODS

Individuals with non-acute major depressive disorder or bipolar affective disorder and healthy participants were recruited. The Composite Scale of Morningness (CSM) and the Pittsburgh Sleep Quality Index (PSQI) were used to evaluate chronotype and sleep quality, respectively. Eysenck Personality Questionnaire, Tridimensional Personality Questionnaire, Perceived Stress Scale, and Beck Anxiety Inventory were used to formulate stress susceptibility and as indicator variables for empirical clustering by latent class analysis (LCA). Linear regression models were used to examine the relationship between chronotype preference and sleep quality. The interaction terms of CSM and stress susceptibility were examined for the moderation effect.

RESULTS

A total of 887 individuals were enrolled in this study, with 68.2% female and 44.1% healthy participants. Three subgroups were derived from LCA and designated as low stresssusceptibility (40.2%), moderate stress susceptibility (40.9%), and high stress susceptibility (18.8%) groups. After controlling for covariates, the CSM scores inversely correlated with PSQI scores [b (se)=-0.02 (0.01), p=0.01], suggesting that individuals with eveningness preferences tend to have poor sleep quality. Moreover, stress susceptibility moderated the relationship between CSM and PSQI scores (p for interaction term = 0.04). Specifically, the inverse association between CSM and PSQI was more robust in the high stress susceptibility group than that in the low stress susceptibility group.

CONCLUSION

Eveningness preference was associated with poor sleep quality, and this relationship was moderated by stress susceptibility.

Identifying diverse forms of (un)healthy sleep: Sleep profiles differentiate adults' psychological and physical well-being

RATIONALE

Sleep health is best described by the co-occurrence of various dimensions (e.g., regularity, daytime alertness, satisfaction, efficiency, duration) but is rarely measured this way. Information is needed regarding common within-person patterns of sleep characteristics among adults and their relative healthiness.

OBJECTIVE

To deepen understanding of healthy and unhealthy sleep, the present study aimed to uncover multidimensional sleep profiles in adults and their associations with a variety of psychological and physical well-being outcomes.

METHODS

Survey data from 4622 adults who participated in the Midlife in the United States (MIDUS) project was used to identify latent sleep profiles across five core sleep dimensions. Adjusting for individual sleep dimensions and sociodemographic covariates, General Linear Models were used to test the associations of sleep profile membership with hedonic and eudemonic well-being and chronic physical conditions.

RESULTS

Four latent sleep profiles were revealed, good sleepers, sufficient but irregular sleepers, nappers, and short, dissatisfied, and inefficient sleepers. The profiles differentially related to well-being outcomes above and beyond individual sleep dimensions and sociodemographic covariates. Good sleepers generally reported the best outcomes, and short, dissatisfied, and inefficient sleepers generally reported the worst outcomes.

CONCLUSION

Four common sleep profiles describe adults' holistic sleep experiences and predict a variety of well-being outcomes beyond other known predictors. In adulthood, healthy sleep may involve sufficient sleep across all dimensions whereas unhealthy sleep may involve insufficient sleep across three key dimensions: duration, satisfaction, and efficiency.

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

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

Eveningness increases risks for depressive and anxiety symptoms and hospital treatments mediated by insufficient sleep in a population-based study of 18,039 adults

BACKGROUND

Epidemiological data show that having the eveningness associates with poor mental health. For preventive measures it is important to know which underlying factors mediate these associations and the burden posed to public health. This study examines at a population-based level, whether (1) circadian type and the sleep-wake behavior-based phase entrainment similarly associate with mental health problems, (2) there are differences in hospital treatments due to mental disorders between chronotypes, and (3) the association of chronotype with mental health is mediated by insufficient sleep.

METHODS

The study sample (N = 18,039) consisted of population-based sample of Finnish adults, aged 25-74 years, with information on their circadian type and sleep patterns, mental health symptoms, and diagnosis as reported in a health examination survey, as well as hospital treatments as recorded on the national Hospital Discharge Register.

RESULTS

All the mental health symptoms, diagnoses and hospital treatments were more pronounced among Evening-types, especially when assessed by circadian type. Insufficient sleep mediated most but not all of the associations between eveningness and mental health.

CONCLUSIONS

Eveningness does not increase mental health risks only on symptom or diagnosis level, but also on hospital admission level. A higher prevalence of insufficient sleep among the Evening-types elevates the risk and severity for many of the mental health outcomes. Improving the sleep among Evening-types could help to improve their mental health prospective and ease the health care burden.

Aberrant functional connectivity between the suprachiasmatic nucleus and the superior temporal gyrus: Bridging RORA gene polymorphism with diurnal mood variation in major depressive disorder

Diurnal mood variation (DMV), a common symptom of major depressive disorder (MDD), is associated with circadian related genes and dysregulation of the suprachiasmatic nucleus (SCN). Previous research confirmed that the RORA gene is involved in the regulation of circadian rhythms. In this study, we hypothesized that polymorphisms of RORA may affect DMV symptoms of MDD through functional changes in the SCN. A total of 208 patients diagnosed with depression and 120 control subjects were enrolled and underwent a resting-state functional magnetic resonance imaging (rs-fMRI). Blood samples were collected and genotyping of 9 RORA gene SNPs were performed using next-generation sequencing technology. Patients were categorized as an AA genotype or C allele carriers based on RORA rs72752802 polymorphism. SCN-seed functional connectivity (FC) was compared between the two groups and correlation with severity of DMV was analyzed. Finally, a mediation analysis was performed to further determine FC intermediary effects. We observed that rs72752802 was significantly associated with patients' DMV symptoms. C allele carriers of rs72752802 showed significantly decreased FC between the right SCN and right superior temporal gyrus (rSTG). This was also correlated with DMV symptoms. In addition, the rs72752802 SNP influenced DMV symptoms through intermediary effects of SCN-rSTG connectivity. The study presented here provides a neurological and genetic basis for understanding depressed patients experiencing DMV.

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

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

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.

The effect of circadian preferences on insomnia severity and depressive symptoms via sleep hygiene in older adults with depression and healthy controls

BACKGROUND

The elderly population is increasing globally. Thus, researches focus on the causes and treatment of insomnia, a noteworthy ageing problem. This study aims to investigate the relationship between chronotype and insomnia and whether sleep hygiene mediates this relationship in older adults with depression (OAD).

METHODS

We assessed subjective insomnia severity, sleep hygiene, chronotype, depressive symptoms, and anxiety symptoms of 82 OAD and 70 healthy controls using the Sleep Hygiene Index (SHI), Insomnia Severity Index (ISI), Morningness-Eveningness Questionnaire (MEQ), Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI).

RESULTS

The mediation effect of SHI and ISI scores were evaluated in the relationship between MEQ and BDI total scores in OAD. The results showed that MEQ performed its effect on BDI through ISI with full mediation (effect = -0.16, SE: 0.07, 95% CI: -0.3230 to -0.0336). The mediation effect of SHI and BDI scores were evaluated in the relationship between MEQ and ISI total scores in OAD. In this model, it was found that MEQ significantly performed its effect on ISI through SHI and BDI. BDI and SHI predicted the ISI variable as partial mediators (respectively, effect = -0.05, SE: 0.03, 95% CI: -0.1073 to -0.0100; effect = -0.06, SE: 0.02, 95% CI: -0.1051 to -0.0129).

CONCLUSIONS

Sleep hygiene practices could be essential for the natural functioning of the biological clock and the interrelation of depression and insomnia. Longitudinal follow-up studies of structured sleep hygiene approaches are needed in terms of cost-effectiveness, in OAD.

Chronotype and psychological distress among Chinese rural population: A moderated mediation model of sleep quality and age

PURPOSES

Evidence suggests evening-type individuals have a higher risk of reporting psychological distress than morning-type individuals. However, less is known regarding the underlying processes that might mediate or moderate this association among Chinese rural population. This study aimed to evaluate the prevalence of psychological distress, investigate whether sleep quality would mediate the association between chronotype and psychological distress and explore whether age would moderate the direct or indirect effect of the mediation model.

METHODS

The cross-sectional study utilized a sample of 884 rural residents from rural regions in Anqing City, Anhui Province, China. Morningness-Eveningness Questionnaire (MEQ), Pittsburgh Sleep Quality Index (PSQI) and 21-item Depression Anxiety Stress Scale (DASS-21) were used to measure chronotype, sleep quality and psychological distress, respectively. MacKinnon's four-step procedure was employed to examine the mediation effect, while Hayes PROCESS macro (model 59) was used to perform the moderated mediation analysis.

RESULTS

The prevalence of psychological distress among Chinese rural population was 33.4%. The association between chronotype and psychological distress was partially mediated by sleep quality (indirect effect = - 0.05, 95% CI = [-0.08, -0.03]). In addition, age moderated the first stage (sleep quality-psychological distress) of the indirect effect, with the indirect effect being attenuated for older rural residents. As suggested by Johnson-Neyman technique, the association between sleep quality and psychological distress was only significant when the age of the participant was lower than 48.59.

CONCLUSIONS

The incidence of psychological distress among Chinese rural residents cannot be neglected. Interventions for the enhancement of sleep quality to prevent and reduce psychological distress should be prioritized to rural residents who are prone to eveningness, especially those who are younger.

Examining the Factor Structure of the Pittsburgh Sleep Quality Index in a Multi-Ethnic Working Population in Singapore

The Pittsburgh Sleep Quality Index (PSQI) is a widely used measure for assessing sleep impairment. Although it was developed as a unidimensional instrument, there is much debate that it contains multidimensional latent constructs. This study aims to investigate the dimensionality of the underlying factor structure of the PSQI in a multi-ethnic working population in Singapore. The PSQI was administered on three occasions (baseline, 3 months and 12 months) to full-time employees participating in a workplace cohort study. Exploratory factor analysis (EFA) investigated the latent factor structure of the scale at each timepoint. Confirmatory factor analysis (CFA) evaluated the model identified by EFA, and additionally evaluated it against a single factor and a three-factor model. The EFA identified a two-factor model with similar internal consistency and goodness-of-fit across each timepoint. In the CFA, the two- and three-factor models were both superior to the unidimensional model. The two- and three-factor models of the PSQI were reliable, consistent and provided similar goodness-of-fit over time, and both models were superior to the unidimensional measure. We recommend using the two-factor model to assess sleep characteristics in working populations in Singapore, given that it performs as well as the three-factor model and is simpler compared to the latter.

Differential associations between chronotype, anxiety, and negative affect: A structural equation modeling approach

BACKGROUND

Increasing evidence implicates circadian rhythms, including chronotype, in anxiety symptoms and disorders. However, it remains unclear whether this relation is accounted for by sleep disturbance. Likewise, given overlap between anxiety and negative affect, a unique link between chronotype and anxiety remains to be established. The present study addressed these questions using a multimethod approach to determine whether there is a unique relation between chronotype and anxiety symptoms, controlling for sleep disturbance.

METHODS

Indicators of chronotype, sleep disturbance, anxiety, and negative affect were collected in a sample of adults (N = 151) using a combination of subjective and behavioral measures both within and outside the laboratory over a 9-day period. Structural equation modeling was used to examine associations between latent constructs.

RESULTS

Results revealed significant associations between sleep disturbance and both anxiety and negative affect. A significant association was found between chronotype and anxiety, over and above the effect of sleep disturbance. In contrast, the relation between chronotype and negative affect was nonsignificant after controlling for sleep disturbance.

LIMITATIONS

Unselected sample, lack of experimental manipulation, cross-sectional design.

CONCLUSIONS

These findings suggest a unique role of chronotype in anxiety and point to circadian disruption as a potential biological mechanism in anxiety-related disorders.

Limbic circuit connectivity and the stress response: New insights into the mammalian nociceptin peptide system

Considerable progress has been made in understanding the neurobehavioral effects of nociceptin peptide (N/OFQ) and its NOP receptor. Recent interest has focused on its role in stress and cognition, with consideration of therapeutic potential in regard to anxiety and mood disorders. Research has interrogated the mechanisms of action of N/OFQ peptide in the context of stress-related behavior. We are interested in the endogenous role of N/OFQ and NOP receptor in terms of adaptation to chronic stress. Our research has highlighted the importance of associated limbic regions including the bed nucleus, extended amygdala, in addition to thalamic reticular nucleus as important sites for long-term adaptations in endogenous N/OFQ function in chronic stress. Such research raises interest in appreciation of extended limbic connections and novel pathways which allow us to reevaluate current understanding of stress neurocircuitry. Examination of endogenous N/OFQ-NOP receptor modulation of monoaminergic and amino acid transmitter systems in this extended limbic architecture will facilitate deeper understanding of the tonic control of behavior. Application of in vivo experimental approaches to models of abnormal neurodevelopment and heightened stress vulnerability in adulthood will enable the role of N/OFQ in complex neuropsychiatric disorders including schizophrenia and post-traumatic stress disorder to be defined.

Chronotype: implications for sleep quality in medical students

Medical students who suffer from poor sleep quality may be afflicted by distress. While the change of chronotype may improve sleep quality, few studies have focused on this association. The objective of this study is to analyze the effects of chronotype on sleep quality in medical students while controlling for confounding covariate factors. A cross-sectional survey on sleep quality was conducted among 5497 medical students. Sleep quality, chronotype, and lifestyle were measured according to the Pittsburgh Sleep Quality Index, Morningness-eveningness Questionnaire and Health-promoting Lifestyle Profile. Hierarchical logistic regression was conducted to analyze the influence of various factors, especially chronotype effect on sleep quality. Our results showed that the total score of sleep quality in evening-types was 5.43 ± 2.66, which was significantly higher than that in morning-types (3.88 ± 2.20, P < .001). Morning-type students (OR = 0.40, 95%CI = 0.29-0.55) and intermediate-type students (OR = 0.53, 95%CI = 0.41-0.69) had a lower risk of poor sleep quality compared to evening-types. The strongest predictor of sleep quality was chronotype while controlling for covariates (grade, gender, father's educational level, mother's educational level, internet addiction, mood state, midnight snack frequency, and health-promoting lifestyle profile). Based on the results, we believe that sleep quality among evening-type students may be improved by shifting to keep early hours.

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.