Genetic Basis of Chronotype in Humans: Insights From Three Landmark GWAS

Relationship between shift type and sleep quality in rotating-shift nurses with chronotype as a moderator variable

BACKGROUND

Rotating-shift nurses are susceptible to sleep disorders due to numerous factors, such as their biological clock, emotions, and age. At present, a lack of research exists on whether chronotype and shift type jointly influence the sleep quality of nurses.

AIM

To verify whether chronotype is a moderator variable of the relationship between shift type and sleep quality in nurses in order to provide empirical evidence for future mental and physical health improvement.

METHOD

Clinical rotating-shift nurses at a medical center in northern Taiwan were recruited as participants between November 1, 2023, and December 13, 2023. All of the nurses were working a monthly rotating shift schedule. Hierarchical multiple regression analysis was employed to investigate whether the influence of shift type on sleep quality in nurses varied with chronotype. The STROBE checklist was used for reporting this study.

RESULTS

The participants were 255 rotating-shift nurses in this study. Hierarchical multiple regression results revealed that rotating-shift nurses who were older (B = 0.19, p = 0.029), had greater physical fatigue (B = 0.27, p = 0.016), and had more negative emotions (B = 0.17, p = 0.011) suffered from poorer sleep quality. After controlling the above factors, we further found that chronotype indeed had moderating effects on the influence of shift type on sleep quality (B = -1.83, p = 0.049).

CONCLUSIONS

This study demonstrates that early- and intermediate-type nurses are more suitable for working the day and evening shifts, whereas late-type nurses are more suitable for working the night shift.

IMPLICATION FOR NURSING AND HEALTH POLICY

Coordinating chronotype with shift type will ensure that shift schedules better match the biological clocks of nurses; such individual considerations could help to improve their sleep quality.

Sleep-wake changes and incident depressive symptoms in midlife women

Our study aimed to investigate the relationship between sleep-wake changes and depressive symptoms events among midlife women. We enrolled 1579 women aged 44-56 years who had no clinically relevant depressive symptoms at baseline. Depressive symptoms were assessed at each visit using the Center for Epidemiologic Studies Depression scale. At the third and fourth follow-up visits, women reported their sleep habits. The sleep midpoint was defined as the time to fall asleep plus one-half of the sleep duration. Sleep-wake changes were determined by the difference in the midpoint of sleep between the third and fourth visits, which were 1 year apart. The median follow-up time was 7 years (range 1-7 years). Cox proportional hazard models were fitted to calculate hazard ratios and 95% confidence intervals for the incidence of depressive symptoms associated with sleep-wake changes. After adjusting for potential confounding factors, the hazard ratio (95% confidence interval) of depressive symptoms for severe sleep midpoint changes was 1.51 (1.12, 2.05) compared with mild sleep midpoint changes. This relationship remained statistically significant and changed little when additionally controlling for sleep duration, sleep quality, insomnia symptoms, use of sleep medications, use of nervous medications, glucose, insulin, lipids, dietary energy intake, and C-reactive protein. Our findings indicate that exposure to long-term severe sleep-wake changes increases the risk of depressive symptoms in midlife women.

The effect of circadian timing program for evening-chronotype individuals with obesity on obesity management and sleep quality: A randomized controlled trial

OBJECTIVES

The study aimed to investigate the effect of the circadian timing program (SİZAP) developed for evening-chronotype individuals with obesity on obesity management and sleep quality.

METHODS

This single-site, randomized controlled trial with an experimental research design was registered in ClinicalTrials.gov. It was reported in accordance with the "Consolidated Standards of Reporting Trials" (CONSORT) randomized controlled trial guidelines. The study sample consisted of 38 evening-chronotype individuals with first-degree obesity, with 19 individuals in each study group. The intervention group's sleep hygiene training was conducted and their lifestyle changes were ensured through SİZAP. The control group followed their normal daily lifestyle. No intervention was made in terms of the dietary practices of both groups. Study data were collected using the personal information form, the anthropometric measurement form, the Horne and Ostberg Morning and Evening Questionnaire (MEQ), the Impact of weight on quality of life-lite (IWQOL-lite), the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), the sleep diary, and the data tracked via the website and smart bracelets.

RESULTS

It was determined that the participants in the SİZAP group had a statistically significant decrease in the anthropometric measurements and daytime sleepiness (p < 0.05). The sleep quality scores and the scores of the bodily functions sub-dimension of the quality of life scale were significantly better in the intervention group than in the control group (p < 0.05).

CONCLUSION

It was found that SİZAP is effective in obesity management in evening-chronotype individuals and increases weight loss success and sleep quality.

High levels of anxiety and depression in women farmers from Ecuador: A cross-section study in Coastal and Highlands regions

BACKGROUND

Previous studies have shown that women farmers are particularly vulnerable to mental health disorders such as depression and anxiety.

AIMS

This study aimed to investigate the prevalence of anxiety and depression in women farmers from Ecuador Coastal and Highlands regions.

METHOD

General Anxiety Disorder‑7 (GAD‑7) and Patient Health Questionnaire‑9 (PHQ‑9) were applied. In addition, self-reported number of children, days off, hours of work, pesticide use, sleep habits and years of work in agriculture, were also collected. This cross-sectional study occurred during 2023 with 443 women, for Coastal (197) and Highlands (246), respectively. Multivariable binary logistic regression models were performed to obtained adjusted odds ratios (aOR) and their 95% confidence intervals (95% CI).

RESULTS

34.5% of Coastal women had depression, while 27.2% of Highlands women had depression. 20.3% of coastal women farmers had anxiety, while in the Highlands 24.8% had anxiety. Coastal mestizo and montubio women exhibited lower probability of depression, but this was not significant in the Highlands. Coastal women farmers that did not have children showed lower odds of depression (aOR 0.05, 95% CI [0.01, 0.34]). A lower likelihood of depression was observed in coastal women that worked more than 8 hours (aOR 0.22, 95% CI [0.07, 0.72]). Women from the Highlands that had shortened sleep duration exhibited lower odds of depression and anxiety.

CONCLUSIONS

A higher proportion of depressed women farmers was observed in the Coast region and slightly higher numbers of anxiety cases in the Highlands. The number of children may cause workload and is correlated with depression in Coastal women.

Genome-Wide Characterization of Somatic Mutation Patterns in Cloned Dogs Reveals Implications for Neuronal Function, Tumorigenesis, and Aging

Studies on somatic mutations in cloned animals have revealed slight genetic variances between clones and their originals, but have yet to identify the precise effects of these differences within the organism. Somatic mutations contribute to aging and are implicated in tumor development and other age-related diseases. Thus, we compared whole genome sequencing data from an original dog with that of cloned dogs, identifying candidate somatic mutations that were disproportionately located within genes previously implicated in aging. The substitutional signature of cloning-specific somatic mutations mirrored the uniform distribution characteristic of the signature associated with human aging. Further analysis of genes revealed significant enrichment of traits associated with body size as well as the molecular mechanisms underlying neuronal function and tumorigenesis. Overall, the somatic mutations found in cloned dogs may indicate a conserved mechanism driving aging across species and a broad spectrum of pathway alterations.

Effect of timed dosing of usual antihypertensives according to patient chronotype on cardiovascular outcomes: the Chronotype sub-study cohort of the Treatment in Morning versus Evening (TIME) study

Background

Timing drug administration to endogenous circadian rhythms may enhance treatment efficacy. In the Chronotype sub-study of the Treatment in Morning versus Evening (TIME) clinical trial we examined whether timing of usual antihypertensive medications according to patient chronotype (a behavioural marker of personal circadian rhythm) may influence clinical cardiovascular outcomes.

Methods

This was a cohort sub-study of TIME, a prospective, randomised, open-label, blinded-endpoint, UK clinical trial of morning versus evening dosing of usual antihypertensive medications and cardiovascular outcomes. On August 3rd, 2020, all active TIME participants were invited to complete a validated chronotype questionnaire. Chronotype was quantitatively assessed as the mid sleep time on free days corrected for sleep debt on workdays (MSFsc). We analysed associations between chronotype and antihypertensive dosing time and explored their combined effect on cardiovascular outcomes (a composite endpoint of hospitalisation for non-fatal myocardial infarction (MI) or non-fatal stroke, and single components) using proportional hazard time-to-event models adjusted for baseline covariates. These were used to specifically test for interactions between dosing time and chronotype.

Findings

Between August 3, 2020, and March 31, 2021, 5358 TIME participants completed the online questionnaire. 2778 were previously randomised to morning dosing and 2580 to evening dosing of their usual antihypertensives. Chronotype was symmetrically distributed around a median MSFsc of 3:07 am. The composite endpoint increased for later MSFsc (later chronotype) dosed in the morning but not in those dosed in the evening (hazard ratios 1.46 [95% CI 1.14-1.86] and 0.96 [95% CI 0.70-1.30] per hour of MSFsc, respectively; interaction p = 0.036). Later chronotype was associated with increased risk of hospitalisation for non-fatal MI in the morning dosing group, and reduced risk in the evening dosing group (hazard ratios 1.62 [95% CI 1.18-2.22] and 0.66 [95% CI 0.44-1.00] per hour of MSFsc, respectively; interaction p < 0.001). No interaction between chronotype and antihypertensive dosing time was observed for stroke events.

Interpretation

Alignment of dosing time of usual antihypertensives with personal chronotype could lower the incidence of non-fatal MI compared to a 'misaligned' dosing time regimen. Future studies are warranted to establish whether synchronizing administration time of antihypertensive therapy with individual chronotype reduces risk of MI.

Funding

The TIME study was funded by the British Heart Foundation (CS/14/1/30659) with support from the British and Irish Hypertension Society.

The effect of cumulative night shift duties on insomnia, fatigue, and mental health in intensive care unit

Background

Night shift duties are crucial in the ICU to ensure care continuity, where critically ill patients require round-the-clock care. However, cumulative night shift duties may disturb circadian rhythm, insomnia, fatigue, and depression, and require further elucidation.

Objectives

This study aims to examine the negative consequences of various night shift patterns on insomnia, fatigue, and mental health of ICU Workers.

Methods

A cross-sectional study examined how cumulative night shift duty affects insomnia, fatigue, and mental health in critical care providers (CCPs).

Results

A total of 1006 participants completed this study between June 2022 and March 2023, including 54.5 % males. About 35 % were between 20 and 30 years of age, and Respiratory Therapists accounted for approximately 46.5 % of the entire sample. Most of our respondents (476; 47 %) reported working night shifts, with a monthly range of 8-15 nights. The prevalence rates for moderate to severe clinical insomnia, fatigue, and moderate to severe depression were 42 %, 48 %, and 32 %, respectively. CCPs working 8-15 nights had a 2-fold risk of clinical insomnia than those working fewer than eight nights with (AOR) and 95 % (CI) of 2.12 and 1.41-3.20, while those working ≥16 nights per month had a greater incidence of clinical insomnia compared to those working <8 nights per month, AOR (CI): 3.09 (1.90-5.03). Only those working ≥16-night shifts per month had a substantially higher fatigue risk compared to those working < 8-night shifts per month, with an AOR (CI) of 1.92 (1.19-3.08). Working 8-15-night shifts per month increases depression risks by 34 % compared to the <8-night shifts group, AOR (CI): 1.34 (0.87-2.08). Those working ≥16-night shifts per month showed a higher depression risk than those working <8-night shifts, AOR (CI): 2.53 (1.53-4.19).

Conclusion

A cumulative night shift above eight nights per month is linked with an increased risk of insomnia, fatigue, and depression. The risk of these conditions was significantly directly proportional to the number of night shifts performed per month.

A genome-wide association study identifies candidate genes for sleep disturbances in depressed individuals

OBJECTIVE

This study aimed to identify candidate loci and genes related to sleep disturbances in depressed individuals and clarify the co-occurrence of sleep disturbances and depression from the genetic perspective.

METHODS

The study subjects (including 58,256 self-reported depressed individuals and 6,576 participants with PHQ-9 score ≥ 10, respectively) were collected from the UK Biobank, which were determined based on the Patient Health Questionnaire (PHQ-9) and self-reported depression status, respectively. Sleep related traits included chronotype, insomnia, snoring and daytime dozing. Genome-wide association studies (GWASs) of sleep related traits in depressed individuals were conducted by PLINK 2.0 adjusting age, sex, Townsend deprivation index and 10 principal components as covariates. The CAUSALdb database was used to explore the mental traits associated with the candidate genes identified by the GWAS.

RESULTS

GWAS detected 15 loci significantly associated with chronotype in the subjects with self-reported depression, such as rs12736689 at RNASEL (P = 1.00 × 10- 09), rs509476 at RGS16 (P = 1.58 × 10- 09) and rs1006751 at RFX4 (P = 1.54 × 10- 08). 9 candidate loci were identified in the subjects with PHQ-9 ≥ 10, of which 2 loci were associated with insomnia such as rs115379847 at EVC2 (P = 3.50 × 10- 08), and 7 loci were associated with daytime dozing, such as rs140876133 at SMYD3 (P = 3.88 × 10- 08) and rs139156969 at ROBO2 (P = 3.58 × 10- 08). Multiple identified genes, such as RNASEL, RGS16, RFX4 and ROBO2 were reported to be associated with chronotype, depression or cognition in previous studies.

CONCLUSION

Our study identified several candidate genes related to sleep disturbances in depressed individuals, which provided new clues for understanding the biological mechanism underlying the co-occurrence of depression and sleep disorders.

Predictors for achieving optimal sleep in healthy children: Exploring sleep patterns in a sleep extension trial

STUDY OBJECTIVES

Earlier bedtimes can help some children get more sleep, but we don't know which children, or what features of their usual sleep patterns could predict success with this approach. Using data from a randomized crossover trial of sleep manipulation, we sought to determine this.

METHODS

Participants were 99 children aged 8-12years (49.5% female) with no sleep disturbances. Sleep was measured by actigraphy at baseline and over a restriction or extension week (1 hour later or earlier bedtime respectively), randomly allocated and separated by a washout week. Data were compared between baseline (week 1) and extension weeks only (week 3 or 5), using linear or logistic regression analyses as appropriate, controlling for randomization order.

RESULTS

One hour less total sleep time than average at baseline predicted 29.7 minutes (95% CI: 19.4, 40.1) of sleep gained and 3.45 (95% CI: 1.74, 6.81) times higher odds of successfully extending sleep by >30 minutes. Per standardized variable, less total sleep time and a shorter sleep period time were the strongest predictors (significant odds ratios (ORs) of 2.51 and 2.28, respectively). Later sleep offset, more variability in sleep timing and lower sleep efficiency also predicted sleep gains. The sleep period time cut-point that optimized prediction of successful sleep gains was <8 hours 28 minutes with 75% of children's baseline sleep in that range.

CONCLUSIONS

Children with a baseline sleep period time <8½ hours a night obtained the most sleep from earlier bedtimes maintained over a week, demonstrating experimentally the value of earlier bedtimes to improve sleep.

CLINICAL TRIALS REGISTRY

Australian New Zealand Clinical Trial Registry, ACTRN12618001671257, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367587&isReview=true.

Meal timing and its role in obesity and associated diseases

Meal timing emerges as a crucial factor influencing metabolic health that can be explained by the tight interaction between the endogenous circadian clock and metabolic homeostasis. Mistimed food intake, such as delayed or nighttime consumption, leads to desynchronization of the internal circadian clock and is associated with an increased risk for obesity and associated metabolic disturbances such as type 2 diabetes and cardiovascular diseases. Conversely, meal timing aligned with cellular rhythms can optimize the performance of tissues and organs. In this review, we provide an overview of the metabolic effects of meal timing and discuss the underlying mechanisms. Additionally, we explore factors influencing meal timing, including internal determinants such as chronotype and genetics, as well as external influences like social factors, cultural aspects, and work schedules. This review could contribute to defining meal-timing-based recommendations for public health initiatives and developing guidelines for effective lifestyle modifications targeting the prevention and treatment of obesity and associated metabolic diseases. Furthermore, it sheds light on crucial factors that must be considered in the design of future food timing intervention trials.

Circadian rhythms and mood disorders: Time to see the light

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

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

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

Role of polygenic risk scores in the association between chronotype and health risk behaviors

BACKGROUND

This study explores the association between chronotypes and adolescent health risk behaviors (HRBs) by testing how genetic background moderates these associations and clarifies the influence of chronotypes and polygenic risk score (PRS) on adolescent HRBs.

METHODS

Using VOS-viewer software to select the corresponding data, this study used knowledge domain mapping to identify and develop the research direction with respect to adolescent risk factor type. Next, DNA samples from 264 students were collected for low-depth whole-genome sequencing. The sequencing detected HRB risk loci, 49 single nucleotide polymorphisms based to significant SNP. Subsequently, PRSs were assessed and divided into low, moderate, and high genetic risk according to the tertiles and chronotypes and interaction models were constructed to evaluate the association of interaction effect and clustering of adolescent HRBs. The chronotypes and the association between CLOCK-PRS and HRBs were examined to explore the association between chronotypes and mental health and circadian CLOCK-PRS and HRBs.

RESULTS

Four prominent areas were displayed by clustering information fields in network and density visualization modes in VOS-viewer. The total score of evening chronotypes correlated with high-level clustering of HRBs in adolescents, co-occurrence, and mental health, and the difference was statistically significant. After controlling covariates, the results remained consistent. Three-way interactions between chronotype, age, and mental health were observed, and the differences were statistically significant. CLOCK-PRS was constructed to identify genetic susceptibility to the clustering of HRBs. The interaction of evening chronotypes and high genetic risk CLOCK-PRS was positively correlated with high-level clustering of HRBs and HRB co-occurrence in adolescents, and the difference was statistically significant. The interaction between the sub-dimensions of evening chronotypes and the high genetic CLOCK-PRS risk correlated with the outcome of the clustering of HRBs and HRB co-occurrence.

CONCLUSIONS

The interaction of PRS and chronotype and the HRBs in adolescents appear to have an association, and the three-way interaction between the CLOCK-PRS, chronotype, and mental health plays important roles for HRBs in adolescents.

Selection of genetic instruments in Mendelian randomisation studies of sleep traits

This review explores the criteria used for the selection of genetic instruments of sleep traits in the context of Mendelian randomisation studies. This work was motivated by the fact that instrument selection is the most important decision when designing a Mendelian randomisation study. As far as we are aware, no review has sought to address this to date, even though the number of these studies is growing rapidly. The review is divided into the following sections which are essential for genetic instrument selection: 1) Single-gene region vs polygenic analysis; 2) Polygenic analysis: biologically-vs statistically-driven approaches; 3) P-value; 4) Linkage disequilibrium clumping; 5) Sample overlap; 6) Type of exposure; 7) Total (R2) and average strength (F-statistic) metrics; 8) Number of single-nucleotide polymorphisms; 9) Minor allele frequency and palindromic variants; 10) Confounding. Our main aim is to discuss how instrumental choice impacts analysis and compare the strategies that Mendelian randomisation studies of sleep traits have used. We hope that our review will enable more researchers to take a more considered approach when selecting genetic instruments for sleep exposures.

Plasma and cerebrospinal fluid proteomic signatures of acutely sleep-deprived humans: an exploratory study

Study Objectives

Acute sleep deprivation affects both central and peripheral biological processes. Prior research has mainly focused on specific proteins or biological pathways that are dysregulated in the setting of sustained wakefulness. This exploratory study aimed to provide a comprehensive view of the biological processes and proteins impacted by acute sleep deprivation in both plasma and cerebrospinal fluid (CSF).

Methods

We collected plasma and CSF from human participants during one night of sleep deprivation and controlled normal sleep conditions. One thousand and three hundred proteins were measured at hour 0 and hour 24 using a high-scale aptamer-based proteomics platform (SOMAscan) and a systematic biological database tool (Metascape) was used to reveal altered biological pathways.

Results

Acute sleep deprivation decreased the number of upregulated and downregulated biological pathways and proteins in plasma but increased upregulated and downregulated biological pathways and proteins in CSF. Predominantly affected proteins and pathways were associated with immune response, inflammation, phosphorylation, membrane signaling, cell-cell adhesion, and extracellular matrix organization.

Conclusions

The identified modifications across biofluids add to evidence that acute sleep deprivation has important impacts on biological pathways and proteins that can negatively affect human health. As a hypothesis-driving study, these findings may help with the exploration of novel mechanisms that mediate sleep loss and associated conditions, drive the discovery of new sleep loss biomarkers, and ultimately aid in the identification of new targets for intervention to human diseases.

Correlation Analysis Between Time Awareness and Morningness-Eveningness Preference

The circadian clock is adjusted by light inputs via the retinohypothalamic tract. Because environmental light is controllable for modern humans at the individual's preference although under social schedules, individual differences in time-related psychology and behavior may be associated with morningness-eveningness preference (M-E preference). To examine this hypothesis, we used the Time Management Scale and Time Anxiety Scale to quantify time-related psychology and behavior. These scales aim to evaluate "awareness of effective time management and utilization" and "anxiety about uncontrollable time schedule and unexpected time-related outcome", respectively. According to our correlation analysis using mid-sleep time as a marker for M-E preference, we obtained results supporting our hypothesis in the correlation between the M-E preference values and the Time Management Scale scores, with larger "time estimation" and "taking each moment as it comes" scores associated with more morningness and eveningness, respectively. Considering that modern humans likely become night owls under artificial light conditions, it appears plausible that lower awareness of time management leads to more eveningness.

Screen time and sleep among medical students in Germany

Medical students are a vulnerable group for harmful health behaviours due to academic stress. Increased screen time is associated with adverse health behaviour, particularly delayed bedtime, shorter sleep duration and poorer sleep quality. This possible relationship has not yet been examined among medical students in Europe. Medical students at the Technical University of Dresden were invited to participate in an online questionnaire based cross-sectional study. To analyse correlations between screen time and sleep parameters, correlation coefficients, linear regression and mixed-model analysis were calculated. 415 students (average age 24 years, 70% female) were included in the analysis. The students reported an average of 7 h screen time per day and 7.25 h sleep duration per night. Approximately 23% (n = 97) reported sleeping less than 7 h per night and 25% (n = 105) reported fairly to very poor sleep quality. Students who reported more screen time for leisure went to bed significantly later (r = 0.213, p < 0.001). Students who spent more screen time for study/work tended to sleep shorter (r = - 0.108, p < 0.015). There was no significant association between screen time and sleep quality (p = 0.103). The results show a need for educational interventions to promote healthy sleep behaviour and to limit screen time.

Circadian preference and physical and cognitive performance in adolescence: A scoping review

Adolescence is a crucial period of development which coincides with changes in circadian rhythmicity. This may augment the impact of circadian preference on performance in this group. We aimed to scope the literature available on chronotypes and their effect on physical and mental aspects of performance in adolescents. Studies were identified by systematically searching bibliographical databases and grey literature. The Morningness-Eveningness Questionnaire was the most frequently reported tool for circadian preference assessment. Academic achievement was the most prevailing outcome, with evidence suggesting that morning type adolescents tend to outperform evening types, yet the results vary depending on multiple factors. Performance in tests of intelligence and executive functions was generally better at optimal times of the day (synchrony effect). Physical performance was examined in 8 studies, with very heterogeneous outcomes. Although the associations between circadian preference and performance in adolescents are evident in some areas, there are many factors that may be involved in the relationship and require further investigation. This review highlights the assessment of physical performance in relation to chronotypes, the multidimensional assessment of circadian preference, and the need for longitudinal studies as priorities for further research.Protocol: OSF Registration - Public registration, DOI: 10.17605/OSF.IO/UCA3Z.

The parasite intraerythrocytic cycle and human circadian cycle are coupled during malaria infection

During infections with the malaria parasites Plasmodium vivax, patients exhibit rhythmic fevers every 48 h. These fever cycles correspond with the time the parasites take to traverse the intraerythrocytic cycle (IEC). In other Plasmodium species that infect either humans or mice, the IEC is likely guided by a parasite-intrinsic clock [Rijo-Ferreiraet al., Science 368, 746-753 (2020); Smith et al., Science 368, 754-759 (2020)], suggesting that intrinsic clock mechanisms may be a fundamental feature of malaria parasites. Moreover, because Plasmodium cycle times are multiples of 24 h, the IECs may be coordinated with the host circadian clock(s). Such coordination could explain the synchronization of the parasite population in the host and enable alignment of IEC and circadian cycle phases. We utilized an ex vivo culture of whole blood from patients infected with P. vivax to examine the dynamics of the host circadian transcriptome and the parasite IEC transcriptome. Transcriptome dynamics revealed that the phases of the host circadian cycle and the parasite IEC are correlated across multiple patients, showing that the cycles are phase coupled. In mouse model systems, host-parasite cycle coupling appears to provide a selective advantage for the parasite. Thus, understanding how host and parasite cycles are coupled in humans could enable antimalarial therapies that disrupt this coupling.

Exploring the associations between the Morningness-Eveningness-Stability-Scale improved (MESSi) and the higher-order personality factors

Morningness-eveningness refers to individual differences in the sleep-wake cycle. Research indicates that morningness-eveningness is associated with the Big Five (neuroticism, extraversion, openness to experience, agreeableness, conscientiousness) and the Big Two (alpha-stability, beta-plasticity) personality factors. However, the latter has not yet been tested within the multidimensional approach to morningness-eveningness. In the present study, we have adapted the Morningness-Eveningness-Stability-Scale improved (MESSi) to Polish (https://osf.io/rcxb5) to explore the associations between its subscales (morning affect, eveningness, distinctness) and the Big Two personality traits in a sample of 1106 participants (559 women and 547 men) aged 18 to 55 (M = 36.26, SD = 9.90). In bivariate correlations, morning affect was positively related to alpha-stability and beta-plasticity, distinctness was correlated negatively with alpha-stability and beta-plasticity, while eveningness was positively correlated only with beta-plasticity. Furthermore, the confirmatory factor analysis supported the original three-factor structure of the Polish version of MESSi, while the associations with affect and the symptoms of depression and anxiety attested to its validity. Overall, the present study provides the first evidence for the associations between MESSi subscales and the Big Two personality traits, as well as shows a good fit of the three-factor structure of MESSi in the Polish population.

Godless owls, devout larks: Religiosity and conscientiousness are associated with morning preference and (partly) explain its effects on life satisfaction

The associations between morningness-eveningness, conscientiousness, and religiosity have not been investigated to date. The aim of the present research was to provide evidence for the relationships between these dimensions. Moreover, we tested whether the well-established link between morningness and life satisfaction could be explained by elevated religiosity of morning-oriented individuals and whether this relationship may be mediated by conscientiousness. The investigation was conducted on two independent samples of Polish adults (N = 500 and N = 728). Our results corroborated earlier findings that morningness was positively associated with both conscientiousness and satisfaction with life. We also found evidence for a significant positive association between morningness and religiosity. Moreover, controlling for age and gender, we obtained significant mediation effects showing that the association between morningness-eveningness and satisfaction with life might stem, at least in part, from the higher religiosity among morning-oriented individuals, also when conscientiousness was included in the model. It means that more morning-oriented individuals may benefit from higher psychological well-being thanks to both personality characteristics and attitudes towards religion.

Differential effects of chronotype on physical activity and cognitive performance in older adults

Introduction

Chronotypes reflect individuals' preferred activity and sleep patterns (e.g., "morning-types" vs. "evening-types") and are associated with health and physical activity. Less is known about the relationship between chronotype and cognitive health in older adults. It is unclear whether chronotype's influence is driven by sleep timing or disruption. This study explored the relationship between chronotype, physical activity, and cognitive performance in older adults with and without self-reported sleep disorders.

Methods

Participants were 153 older adults (M = 70.35, SD = 5.89) who wore an Actigraph on the non-dominant wrist for seven days to measure total physical activity, peak physical activity, and chronotype (sleep interval midpoint). We categorized participants as morning-, evening-, and intermediate-chronotypes and assessed cognitive performance in domains of attention, executive function, and verbal memory.

Results

MANCOVAs showed patterns of activity across the 24-hour day differed between chronotypes such that morning-types were active earlier and evening-types active later, ps > .001. Total physical activity and average peak activity did not differ between chronotypes, (ps ≥ .117). Timing of peak activity followed expectations (morning-types peaked earliest (p = .019). Evening-types exhibited significantly worse executive function and attention than intermediate-types, p = .008. When excluding participants with sleep disorders, evening-types engaged in significantly less total physical activity than other groups, but cognitive performance did not differ.

Discussion

We found no differences in total or peak physical activity between groups, which is inconsistent with findings from studies in younger samples. This suggests the role of chronotype on physical activity may change with age and points to the potential impact of methodological discrepancies. While evening-types exhibited worse executive function and attention performance, this finding disappeared when participants with sleep disorders were excluded. Sleep dysregulation rather than sleep timing may be driving this difference. Recent trends in physical activity research explore activity patterns across the 24-hour day and acknowledge codependence between different activity types. Our findings suggest chronotype and activity timing may be important as researchers advance this line of research in older adults.

Physiological Rhythms and Biological Variation of Biomolecules: The Road to Personalized Laboratory Medicine

The concentration of biomolecules in living systems shows numerous systematic and random variations. Systematic variations can be classified based on the frequency of variations as ultradian (<24 h), circadian (approximately 24 h), and infradian (>24 h), which are partly predictable. Random biological variations are known as between-subject biological variations that are the variations among the set points of an analyte from different individuals and within-subject biological variation, which is the variation of the analyte around individuals’ set points. The random biological variation cannot be predicted but can be estimated using appropriate measurement and statistical procedures. Physiological rhythms and random biological variation of the analytes could be considered the essential elements of predictive, preventive, and particularly personalized laboratory medicine. This systematic review aims to summarize research that have been done about the types of physiological rhythms, biological variations, and their effects on laboratory tests. We have searched the PubMed and Web of Science databases for biological variation and physiological rhythm articles in English without time restrictions with the terms “Biological variation, Within-subject biological variation, Between-subject biological variation, Physiological rhythms, Ultradian rhythms, Circadian rhythm, Infradian rhythms”. It was concluded that, for effective management of predicting, preventing, and personalizing medicine, which is based on the safe and valid interpretation of patients’ laboratory test results, both physiological rhythms and biological variation of the measurands should be considered simultaneously.

Beyond sleep: A multidimensional model of chronotype

Chronotype can be defined as an expression or proxy for circadian rhythms of varied mechanisms, for example in body temperature, cortisol secretion, cognitive functions, eating and sleeping patterns. It is influenced by a range of internal (e.g., genetics) and external factors (e.g., light exposure), and has implications for health and well-being. Here, we present a critical review and synthesis of existing models of chronotype. Our observations reveal that most existing models and, as a consequence, associated measures of chronotype have focused solely or primarily on the sleep dimension, and typically have not incorporated social and environmental influences on chronotype. We propose a multidimensional model of chronotype, integrating individual (biological and psychological), environmental and social factors that appear to interact to determine an individual's true chronotype with potential feedback loops between these factors. This model could be beneficial not only from a basic science perspective but also in the context of understanding health and clinical implications of certain chronotypes as well as designing preventive and therapeutic approaches for related illnesses.

Chronotype, sleep, and sleepiness in Parkinson's disease

We aimed to determine the distribution of chronotypes in a cohort of PD patients and to evaluate the relationships between chronotype and PD characteristics, and self-reported metrics of sleep and sleepiness. Chronotype was characterized using the Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ). PD participants were categorized as Evening Types (ET), Neither Types (NT), or Morning Types (MT). Sleepiness was assessed by the Epworth Sleepiness Scale. Sleep metrics included self-reported sleep times and latency. 186 participants with PD, age 65.5 ± 9.8 yrs, disease duration 6.17 ± 6.7 yrs completed the MEQ. Most participants were classified as MT (63.4%). Participants in the ET group were younger than those in the NT and MT groups (57.6 ± 6.3 vs 67.3 ± 10.2 vs 64.9 ± 9.5). The mean disease duration was not different among chronotypes. No significant relationship between chronotype and sleepiness was found. MT participants woke up and went to bed significantly earlier than NT participants. There was no significant difference between chronotypes and PD medications. Further studies should examine if PD severity and progression affect the chronotype, and whether certain chronotype differentially affects the quality of life, symptom control, and medication effectiveness in the PD population.

Chrononutrition-When We Eat Is of the Essence in Tackling Obesity

Obesity is a chronic and relapsing public health problem with an extensive list of associated comorbidities. The worldwide prevalence of obesity has nearly tripled over the last five decades and continues to pose a serious threat to wider society and the wellbeing of future generations. The pathogenesis of obesity is complex but diet plays a key role in the onset and progression of the disease. The human diet has changed drastically across the globe, with an estimate that approximately 72% of the calories consumed today come from foods that were not part of our ancestral diets and are not compatible with our metabolism. Additionally, multiple nutrient-independent factors, e.g., cost, accessibility, behaviours, culture, education, work commitments, knowledge and societal set-up, influence our food choices and eating patterns. Much research has been focused on 'what to eat' or 'how much to eat' to reduce the obesity burden, but increasingly evidence indicates that 'when to eat' is fundamental to human metabolism. Aligning feeding patterns to the 24-h circadian clock that regulates a wide range of physiological and behavioural processes has multiple health-promoting effects with anti-obesity being a major part. This article explores the current understanding of the interactions between the body clocks, bioactive dietary components and the less appreciated role of meal timings in energy homeostasis and obesity.

Chronovaccination: Harnessing circadian rhythms to optimize immunisation strategies

Vaccination, as a public health measure, offers effective protection of populations against infectious diseases. Optimising vaccination efficacy, particularly for higher-risk individuals, like the elderly whose immunocompromised state can prevent the development of robust vaccine responses, is vital. It is now clear that 24-hour circadian rhythms, which govern virtually all aspects of physiology, can generate oscillations in immunological responses. Consequently, vaccine efficacy may depend critically on the time of day of administration(s), including for Covid-19, current vaccines, and any future diseases or pandemics. Published clinical vaccine trials exploring diurnal immune variations suggest this approach could represent a powerful adjunct strategy for optimising immunisation, but important questions remain to be addressed. This review explores the latest insights into diurnal immune variation and the outcomes of circadian timing of vaccination or 'chronovaccination'.

Circadian rhythms and disorders of the timing of sleep

The daily alternation between sleep and wakefulness is one of the most dominant features of our lives and is a manifestation of the intrinsic 24 h rhythmicity underlying almost every aspect of our physiology. Circadian rhythms are generated by networks of molecular oscillators in the brain and peripheral tissues that interact with environmental and behavioural cycles to promote the occurrence of sleep during the environmental night. This alignment is often disturbed, however, by contemporary changes to our living environments, work or social schedules, patterns of light exposure, and biological factors, with consequences not only for sleep timing but also for our physical and mental health. Characterised by undesirable or irregular timing of sleep and wakefulness, in this Series paper we critically examine the existing categories of circadian rhythm sleep-wake disorders and the role of the circadian system in their development. We emphasise how not all disruption to daily rhythms is driven solely by an underlying circadian disturbance, and take a broader, dimensional approach to explore how circadian rhythms and sleep homoeostasis interact with behavioural and environmental factors. Very few high-quality epidemiological and intervention studies exist, and wider recognition and treatment of sleep timing disorders are currently hindered by a scarcity of accessible and objective tools for quantifying sleep and circadian physiology and environmental variables. We therefore assess emerging wearable technology, transcriptomics, and mathematical modelling approaches that promise to accelerate the integration of our knowledge in sleep and circadian science into improved human health.

Causal relationship between insomnia and tuberculosis: A bi-directional Mendelian randomization analysis

Previous observational studies appear to have established a bi-directional association between sleep disorders and tuberculosis. However, their conclusions are prone to be biased by confounding effects and reverse causation due to the nature of observational studies. Mendelian randomization (MR) approach provides unconfounded estimates of causal effects and overcomes the limitations of observational studies. We performed a bi-directional MR analysis to clarify whether there existed a causal effect of insomnia on tuberculosis, or tuberculosis on insomnia. In forward-direction MR, we chose genome-wide significant (P < .5 × 10-8) and independent (r2 < 0.001) single-nucleotide polymorphisms (SNPs) as instrumental variants (IVs), then extracted effect estimates of these IVs in tuberculosis genome-wide association study (GWAS) dataset to explore causal effect of genetically proxied insomnia on tuberculosis using inverse variance-weighted (IVW), MR-Egger, and weighted median methods. Additionally, we examined robustness and pleiotropy of effect estimates by heterogeneity and sensitivity analysis. Similarly, we investigated causal effect of genetically proxied tuberculosis on insomnia in reverse-direction MR. We revealed no causal relationship between genetically proxied insomnia and tuberculosis using 15 SNPs in forward-direction MR (IVW OR 5.305 [0.100-281.341], P = .410) and reverse-direction MR analysis (ORs and P values were not applicable due to no eligible SNPs in GWAS), with insignificant heterogeneity (Q = 22.6, I2 < 0.001, P = .066) and pleiotropy (intercept = 0.032, SE = 0.057, P = .592) in effect estimates. Our bi-directional MR analysis affirms no causal effect of insomnia on tuberculosis, or tuberculosis on insomnia.

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

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

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.

Exome-wide screening identifies novel rare risk variants for major depression disorder

Despite thousands of common genetic loci of major depression disorders (MDD) have been identified by GWAS to date, a large proportion of genetic variation predisposing to MDD remains unaccounted for. By utilizing the newly released UK Biobank 200,643 exome dataset, we conducted an exome-wide association study to identify rare risk variants contributing to MDD. After quality control, 120,033 participants with MDD polygenic risk scores (PRS) values were included. The individuals with lower 30% quantile of the PRS value were filtered for case and control selecting. Then the cases were set as the individuals with upper 10% quantile of the PHQ depression score and lower 10% quantile were set as controls. Finally, 1612 cases and 1612 controls were included in this study. The variants were annotated by ANNOVRA software. After exclusions, 34,761 qualifying variants, including 148 frameshift variant, 335 non-frameshift variant, 33,758 nonsynonymous, 91 start-loss, 393 stop-gain, 36 stop-loss variants were imported into the SKAT R-package to perform single variants, gene-based burden and robust burden tests with minor allele frequency (MAF) < 0.01. Single variant association testing identified one variant, rs4057749 (P = 5.39 × 10^-9), within OR8B4 gene at an exome-wide significance level. The gene-based burden test of the exonic variants identified genome-wide significant associations in OR8B4 (P_SKAT = 6.23 × 10^-5, P_{SKAT Robust} = 4.49 × 10^-5), TRAPPC11 (P_SKAT = 0.014, P_{SKAT Robust} = 0.015), SBK3 (P_SKAT = 0.020, P_{SKAT Robust} = 0.025) and TNRC6B (P_SKAT = 0.026, P_{SKAT Robust} = 0.036). We identified multiple novel rare risk variants contributing to MDD in the individuals with lower PRS of MDD. The findings can help to broaden the genetic insights of the MDD pathogenesis.

Prevalence and risk factors for depression among training physicians in China and the United States

During their first year of medical residency (internship), 35% of training physicians in the United States suffer at least one depression episode. We assessed whether there is a similar increase of depression among first year residents in China, and identified predictors of depression in the two systems. 1006 residents across three cohorts (2016-2017, 2017-2018 and 2018-2019) at Shanghai Jiao Tong University and Peking Union Medical College were assessed in parallel with three cohorts of 7028 residents at 100 + US institutions. The Patient Health Questionnaire-9 (PHQ-9) depressive symptoms were measured at baseline and quarterly. Demographic, personal and residency factors were assessed as potential predictors of PHQ-9 depression scores. Similar to training interns in the US, the proportion of participants in China who met depression criteria at least once during the first year of residency increased substantially, from 9.1 to 35.1%. History of depression and symptoms at baseline were common factors significantly associated with depression during residency. By contrast, neuroticism, early family environment, female gender and not being coupled were associated with depression risk only in the US, while young age was a predictor of depression only in China. Fear of workplace violence also was a predictor in China. Long duty hours and reduced sleep duration emerged as training predictors of depression in both countries. The magnitude of depression increase and work-related drivers of depression were similar between China and the US, suggesting a need for effective system reforms in both systems.

Treatment of Circadian Rhythm Sleep-Wake Disorders

Circadian rhythm sleep-wake disorders (CRSWDs) are a distinct class of sleep disorders caused by alterations to the circadian time-keeping system, its entrainment mechanisms, or a mismatch between the endogenous circadian rhythm and the external environment. The main clinical manifestations are insomnia and excessive daytime sleepiness that often lead to clinically meaningful distress or cause mental, physical, social, occupational, educational, or other functional impairment. CRSWDs are easily mistaken for insomnia or early waking up, resulting in inappropriate treatment. CRSWDs can be roughly divided into two categories, namely, intrinsic CRSWDs, in which sleep disturbances are caused by alterations to the endogenous circadian rhythm system due to chronic changes in the regulation or capture mechanism of the biological clock, and extrinsic circadian rhythm sleep-wake disorders, in which sleep disorders, such as jet lag or shift-work disorder, result from environmental changes that cause a mismatch between sleep-wakefulness times and internal circadian rhythms. Sleep diaries, actigraphy, and determination of day and night phase markers (dim light melatonin onset and core body temperature minimum) have all become routine diagnostic methods for CRSWDs. Common treatments for CRSWD currently include sleep health education, time therapy, light therapy, melatonin, and hypnotic drug therapy. Here, we review the progress in the epidemiology, etiology, diagnostic evaluation, diagnostic criteria, and treatment of intrinsic CRSWD, with emphasis on the latter, in the hope of bolstering the clinical diagnosis and treatment of CRSWDs.

Population-specific association of Clock gene polymorphism with annual cycle timing in stonechats

Timing is essential for survival and reproduction of organisms across the tree of life. The core circadian clock gene Clk is involved in the regulation of annual timing events and shows highly conserved sequence homology across vertebrates except for one variable region of poly-glutamine repeats. Clk genotype varies in some species with latitude, seasonal timing and migration. However, findings are inconsistent, difficult to disentangle from environmental responses, and biased towards high latitudes. Here we combine field data with a common-garden experiment to study associations of Clk polymorphism with latitude, migration and annual-cycle timing within the stonechat species complex across its trans-equatorial distribution range. Our dataset includes 950 records from 717 individuals from nine populations with diverse migratory strategies. Gene diversity was lowest in resident African and Canary Island populations and increased with latitude, independently of migration distance. Repeat length and annual-cycle timing was linked in a population-specific way. Specifically, equatorial African stonechats showed delayed timing with longer repeat length for all annual-cycle stages. Our data suggest that at low latitudes with nearly constant photoperiod, Clk genotype might orchestrate a range of consistent, individual chronotypes. In contrast, the influence of Clk on annual-cycle timing at higher latitudes might be mediated by its interactions with genes involved in (circadian) photoperiodic pathways.

Neurobiological and behavioral mechanisms of circadian rhythm disruption in bipolar disorder: A critical multi-disciplinary literature review and agenda for future research from the ISBD task force on chronobiology

AIM

Symptoms of bipolar disorder (BD) include changes in mood, activity, energy, sleep, and appetite. Since many of these processes are regulated by circadian function, circadian rhythm disturbance has been examined as a biological feature underlying BD. The International Society for Bipolar Disorders Chronobiology Task Force (CTF) was commissioned to review evidence for neurobiological and behavioral mechanisms pertinent to BD.

METHOD

Drawing upon expertise in animal models, biomarkers, physiology, and behavior, CTF analyzed the relevant cross-disciplinary literature to precisely frame the discussion around circadian rhythm disruption in BD, highlight key findings, and for the first time integrate findings across levels of analysis to develop an internally consistent, coherent theoretical framework.

RESULTS

Evidence from multiple sources implicates the circadian system in mood regulation, with corresponding associations with BD diagnoses and mood-related traits reported across genetic, cellular, physiological, and behavioral domains. However, circadian disruption does not appear to be specific to BD and is present across a variety of high-risk, prodromal, and syndromic psychiatric disorders. Substantial variability and ambiguity among the definitions, concepts and assumptions underlying the research have limited replication and the emergence of consensus findings.

CONCLUSIONS

Future research in circadian rhythms and its role in BD is warranted. Well-powered studies that carefully define associations between BD-related and chronobiologically-related constructs, and integrate across levels of analysis will be most illuminating.

Familial natural short sleep mutations reduce Alzheimer pathology in mice

Although numerous studies have demonstrated that poor sleep increases the development of AD, direct evidence elucidating the benefits of good sleep on the AD pathogenesis is lacking. Familial Natural Short Sleepers (FNSS) are genetically wired to have lifelong reduction in nightly sleep duration without evident consequence on cognitive demise, implying that they may have better sleep quality. Here we investigated two FNSS mutations, DEC2-P384R and Npsr1-Y206H, on the development of tau and amyloid pathology in AD-like mouse models. We found that the development of tau pathology is attenuated in the hippocampus of tau mice carrying FNSS mutations. We also found that DEC2-P384R;5XFAD and female Npsr1-Y206H;5XFAD mice exhibit significantly less amyloid plaques than control mice at 6 months of age. Together, these results reveal that these two FNSS alleles are strong genetic modifiers of AD pathology and may confer resilience to the progression of tau pathology and amyloid plaque formation in neurodegeneration.

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Two FNSS mutations are strong genetic modifiers of AD-like pathology in mice

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Mutant DEC2 and Npsr1 reduced tau pathology in PS19 mouse model of tauopathy

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Mutant DEC2 and Npsr1 slowed down amyloid plaques in 5XFAD APP transgenic mouse model

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Efficient sleep may be an exciting therapeutic target for ameliorating AD development

Adaptation and Pilot Study of a Behavioral Intervention Targeting Morning Activation Deficits in Dementia Caregivers: Scheduling Activity and Monitoring Mornings (SAMM)

OBJECTIVES

Morning activation deficits (MADs) correlate with depression symptom persistence in older dementia caregivers. To clarify the potential of MADs as a target for depression interventions, we aimed to: 1) adapt an existing behavioral activation program, Engage therapy, to target mornings; and 2) evaluate effects on self-reported MADs and depression symptoms.

METHODS

While trialing the 9-week Engage adaption (targeting mornings) in six older dementia caregivers, we incorporated feedback and finalized an adapted program called Scheduling Activity and Monitoring Mornings (SAMM). We delivered the SAMM protocol to 13 dementia caregivers (all female; mean age = 69, standard deviation = 7). We report modifications made/rationale, as well as changes in subjective MADs (relevant items from the Composite Scale of Morningness) and depression symptoms (Patient Health Questionnaire - 9).

RESULTS

Using caregiver and expert input, we adapted the protocol to: include educational materials/content describing the potential relationship between morning inactivity and depression; target activity scheduling within 2 hours of awakening (preferably earlier); and focus only on the main components of morning activity scheduling, planning, and monitoring. This program was associated with decreases in subjective MADs averaging 29% at week 4, 52% at week 6, and 57% by week 9 (all p's <0.005). Initial depression symptoms were significantly reduced, by 62%, at week 9.

CONCLUSIONS

These preliminary findings suggest that subjective MADs can be modified pragmatically, and that doing so may have antidepressant effects. A controlled trial with measures of the putative mechanism is needed to clarify whether, and if so how, targeting MAD with SAMM causally perturbs depression's mechanisms.

Foundations of circadian medicine

The circadian clock is an evolutionarily highly conserved endogenous timing program that structures physiology and behavior according to the time of day. Disruption of circadian rhythms is associated with many common pathologies. The emerging field of circadian medicine aims to exploit the mechanisms of circadian physiology and clock-disease interaction for clinical diagnosis, treatment, and prevention. In this Essay, we outline the principle approaches of circadian medicine, highlight the development of the field in selected areas, and point out open questions and challenges. Circadian medicine has unambiguous health benefits over standard care but is rarely utilized. It is time for clock biology to become an integrated part of translational research.

Chronoradiobiology of Breast Cancer: The Time Is Now to Link Circadian Rhythm and Radiation Biology

Circadian disruption has been linked to cancer development, progression, and radiation response. Clinical evidence to date shows that circadian genetic variation and time of treatment affect radiation response and toxicity for women with breast cancer. At the molecular level, there is interplay between circadian clock regulators such as PER1, which mediates ATM and p53-mediated cell cycle gating and apoptosis. These molecular alterations may govern aggressive cancer phenotypes, outcomes, and radiation response. Exploiting the various circadian clock mechanisms may enhance the therapeutic index of radiation by decreasing toxicity, increasing disease control, and improving outcomes. We will review the body’s natural circadian rhythms and clock gene-regulation while exploring preclinical and clinical evidence that implicates chronobiological disruptions in the etiology of breast cancer. We will discuss radiobiological principles and the circadian regulation of DNA damage responses. Lastly, we will present potential rational therapeutic approaches that target circadian pathways to improve outcomes in breast cancer. Understanding the implications of optimal timing in cancer treatment and exploring ways to entrain circadian biology with light, diet, and chronobiological agents like melatonin may provide an avenue for enhancing the therapeutic index of radiotherapy.

Genome-Wide Association Study and Genetic Correlation Scan Provide Insights into Its Genetic Architecture of Sleep Health Score in the UK Biobank Cohort

PURPOSE

Most previous genetic studies of sleep behaviors were conducted individually, without comprehensive consideration of the complexity of various sleep behaviors. Our aim is to identify the genetic architecture and potential biomarker of the sleep health score, which more powerfully represents overall sleep traits.

PATIENTS AND METHODS

We conducted a genome-wide association study (GWAS) of sleep health score (overall assessment of sleep duration, snoring, insomnia, chronotype, and daytime dozing) using 336,463 participants from the UK Biobank. Proteome-wide association study (PWAS) and transcriptome-wide association study (TWAS) were then performed to identify candidate genes at the protein and mRNA level, respectively. We finally used linkage disequilibrium score regression (LDSC) to estimate the genetic correlations between sleep health score and other functionally relevance traits.

RESULTS

GWAS identified multiple variants near known candidate genes associated with sleep health score, such as MEIS1, FBXL13, MED20 and SMAD5. HDHD2 (PPWAS = 0.0146) and GFAP (PPWAS = 0.0236) were identified associated with sleep health score by PWAS. TWAS identified ORC4 (PTWAS = 0.0212) and ZNF732 (PTWAS = 0.0349) considering mRNA expression level. LDSC found significant genetic correlations of sleep health score with 3 sleep behaviors (including insomnia, snoring, dozing), 4 psychiatry disorders (major depressive disorder, attention deficit/hyperactivity disorder, schizophrenia, autism spectrum disorder), and 9 plasma protein (such as Stabilin-1, Stromelysin-2, Cytochrome c) (all LDSC PLDSC < 0.05).

CONCLUSION

Our results advance the comprehensive understanding of the aetiology and genetic architecture of the sleep health score, refine the understanding of the relationship of sleep health score with other traits and diseases, and may serve as potential targets for future mechanistic studies of sleep phenotype.

The Association Between Morningness-Eveningness Preference, Depression, Anxiety and Insomnia Among Chinese Textile Workers With or Without Shift Work

OBJECTIVE

Circadian preference and mental health disorders are closely related to insomnia. This study aimed to evaluate insomnia symptoms in textile factory workers with different work schedules, and to investigate the association between insomnia, morningness-eveningness preference, anxiety, and depression.

METHODS

A total of 3,883 textile workers were assessed using the 3-items of Pittsburg Sleep Quality Index, Composite Scale of Morningness, Beck Anxiety Inventory, Center for Epidemiologic Studies-Depression Scale, and socio-demographic questionnaires.

RESULTS

The prevalence rate of insomnia in textile workers was 16.7% (N = 646), with 49.8% (N = 322) were shift workers. Among shift workers (N = 1,833), 9.5% had difficulty initiating sleep, and almost 9.0% suffered from early morning awakening, a rate significantly higher than among daytime workers. Logistics regressions revealed that work schedule was insignificantly associated with insomnia. Depression (OR = 1.034, 95% CI = 1.022-1.046) and anxiety (OR = 1.031, 95% CI = 1.018-1.043) positively predicted insomnia, whereas morningness preference (OR = 0.977, 95% CI = 0.960-0.995) decreased the likelihood of insomnia. Furthermore, mediation analysis showed that both anxiety and depression independently mediated the association between circadian preferences and insomnia in textile workers with or without shift work.

CONCLUSION

This study highlighted the insomnia, depression, and anxiety of textile factory workers in a Chinese textile factory. To improve insomnia symptoms, interventions to promote morningness circadian preference and reduce depressive and anxious symptoms among workers are encouraged.

Do sex hormones confound or mediate the effect of chronotype on breast and prostate cancer? A Mendelian randomization study

Morning-preference chronotype has been found to be protective against breast and prostate cancer. Sex hormones have been implicated in relation to chronotype and the development of both cancers. This study aimed to assess whether sex hormones confound or mediate the effect of chronotype on breast and prostate cancer using a Mendelian Randomization (MR) framework. Genetic variants associated with chronotype and sex hormones (total testosterone, bioavailable testosterone, sex hormone binding globulin, and oestradiol) (p<5×10-8) were obtained from published genome-wide association studies (n≤244,207 females and n≤205,527 males). These variants were used to investigate causal relationships with breast (nCases/nControls = 133,384/113,789) and prostate (nCases/nControls = 79,148/61,106) cancer using univariable, bidirectional and multivariable MR. In females, we found evidence for: I) Reduced risk of breast cancer per category increase in morning-preference (OR = 0.93, 95% CI:0. 88, 1.00); II) Increased risk of breast cancer per SD increase in bioavailable testosterone (OR = 1.10, 95% CI: 1.01, 1.19) and total testosterone (OR = 1.15, 95% CI:1.07, 1.23); III) Bidirectional effects between morning-preference and both bioavailable and total testosterone (e.g. mean SD difference in bioavailable testosterone = -0.08, 95% CI:-0.12, -0.05 per category increase in morning-preference vs difference in morning-preference category = -0.04, 95% CI: -0.08, 0.00 per SD increase in bioavailable testosterone). In males, we found evidence for: I) Reduced risk of prostate cancer per category increase in morning-preference (OR = 0.90, 95% CI: 0.83, 0.97) and II) Increased risk of prostate cancer per SD increase in bioavailable testosterone (OR = 1.22, 95% CI: 1.08, 1.37). No bidirectional effects were found between morning-preference and testosterone in males. While testosterone levels were causally implicated with both chronotype and cancer, there was inconsistent evidence for testosterone as a mediator of the relationship. The protective effect of morning-preference on both breast and prostate cancer is clinically interesting, although it may be difficult to effectively modify chronotype. Further studies are needed to investigate other potentially modifiable intermediates.

Multi-Modal Regulation of Circadian Physiology by Interactive Features of Biological Clocks

The circadian clock is a fundamental biological timing mechanism that generates nearly 24 h rhythms of physiology and behaviors, including sleep/wake cycles, hormone secretion, and metabolism. Evolutionarily, the endogenous clock is thought to confer living organisms, including humans, with survival benefits by adapting internal rhythms to the day and night cycles of the local environment. Mirroring the evolutionary fitness bestowed by the circadian clock, daily mismatches between the internal body clock and environmental cycles, such as irregular work (e.g., night shift work) and life schedules (e.g., jet lag, mistimed eating), have been recognized to increase the risk of cardiac, metabolic, and neurological diseases. Moreover, increasing numbers of studies with cellular and animal models have detected the presence of functional circadian oscillators at multiple levels, ranging from individual neurons and fibroblasts to brain and peripheral organs. These oscillators are tightly coupled to timely modulate cellular and bodily responses to physiological and metabolic cues. In this review, we will discuss the roles of central and peripheral clocks in physiology and diseases, highlighting the dynamic regulatory interactions between circadian timing systems and multiple metabolic factors.

Actigraphy-Derived Sleep Profiles of Children with and without Attention-Deficit/Hyperactivity Disorder (ADHD) over Two Weeks-Comparison, Precursor Symptoms, and the Chronotype

Although sleep problems are common in children with ADHD, their extent, preceding risk factors, and the association between neurocognitive performance and neurobiological processes in sleep and ADHD, are still largely unknown. We examined sleep variables in school-aged children with ADHD, addressing their intra-individual variability (IIV) and considering potential precursor symptoms as well as the chronotype. Additionally, in a subgroup of our sample, we investigated associations with neurobehavioral functioning (n = 44). A total of 57 children (6-12 years) with (n = 24) and without ADHD (n = 33) were recruited in one center of the large ESCAlife study to wear actigraphs for two weeks. Actigraphy-derived dependent variables, including IIV, were analyzed using linear mixed models in order to find differences between the groups. A stepwise regression model was used to investigate neuropsychological function. Overall, children with ADHD showed longer sleep onset latency (SOL), higher IIV in SOL, more movements during sleep, lower sleep efficiency, and a slightly larger sleep deficit on school days compared with free days. No group differences were observed for chronotype or sleep onset time. Sleep problems in infancy predicted later SOL and the total number of movements during sleep in children with and without ADHD. No additional effect of sleep problems, beyond ADHD symptom severity, on neuropsychological functioning was found. This study highlights the importance of screening children with ADHD for current and early childhood sleep disturbances in order to prevent long-term sleep problems and offer individualized treatments. Future studies with larger sample sizes should examine possible biological markers to improve our understanding of the underlying mechanisms.

Sleep-wake rhythm and its association with lifestyle, health-related quality of life and academic performance among Japanese nursing students: a cross-sectional study

Background

Young adults are likely to have activities and go to bed late at night due to their age-dependent delayed endogenous circadian clock. The purpose of the present study was to clarify sleep–wake rhythm and its association with lifestyle, health-related quality of life, and academic performance among nursing students.

Methods

Self-reported questionnaires were distributed to undergraduate nursing students at six universities in Japan. Sleep–wake rhythm was assessed using the morningness-eveningness questionnaire. A quantitative design using the generalized linear mixed effect model was utilized to identify the factors related to the evening type among female nursing students (n = 447).

Results

About 18% of the participants were identified as the evening type. Evening type was associated with living alone, part-time job, and club activity. Sleep duration on weekdays was shorter, meal time duration was the shortest, and the percentages of students who skipped meals and those who gained body weight were higher in the evening type than in the morning type and intermediate type. Mental health-related quality of life was lower in the intermediate type and evening type than in the morning type, while there was no difference in physical health-related quality of life among these groups. The percentages of the nursing students who have experienced absence, tardiness, falling asleep during class, and/or interference with academic achievement were higher in the evening type than in other groups.

Conclusions

The present study has important implications for nursing students’ biological characteristics and lifestyle, which are associated with their health-related quality of life and academic performance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12912-021-00748-3.