PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Chronotype”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

14 recordsLinked to original sources
PubMed2026

Genetic evidence for causality of late chronotype on metabolic syndrome in East Asians and Europeans.

CONTEXT: The impact of chronotype-defined as an individuals' inherent preference of sleep timing-and its genetic determinants on metabolic syndrome (MetS) has been less studied. OBJECTIVE: This study investigated the causal relationship between late chronotype and MetS using Mendelian randomization (MR) analysis, based on data from the Taiwan Biobank (TWB) and parallel analyses in the UK Biobank (UKB). METHODS: A total of 36,845 participants from TWB served as the discovery cohort, and 235,639 participants from UKB served as the replication cohort. Late chronotype was defined in TWB as a preference for bedtime after midnight, and in UKB as self-report as being an 'evening' person. The association between late chronotype and MetS, along with its components, was evaluated in TWB, and validated in UKB. Genome-wide association analyses for late chronotype were first conducted in TWB and then meta-analyzed with UKB. Polygenic risk scores (PRS) for late chronotype were constructed and tested for association with MetS. Causality between late chronotype and MetS was examined using one-sample MR analysis in TWB and validated in UKB. RESULTS: Late chronotype was significantly associated with MetS, as well as with central obesity, hyperglycemia, and hypertriglyceridemia, in both TWB and UKB (all P&#xa0;<&#xa0;0.0083, considering Bonferroni correction). The constructed PRS of late chronotype also showed significant associations with MetS and several of its components (several P&#xa0;<&#xa0;0.0083, considering Bonferroni correction). Findings from the one-sample MR analysis indicated a potential causal effect of late chronotype on MetS. CONCLUSIONS: This study provides evidence of a robust association between late chronotype and MetS across populations of diverse ancestry, including Taiwanese and European.

Humans↗
PubMed2025

Genetic prediction of early adolescent chronotype: effects of sex and pubertal status.

STUDY OBJECTIVES: Adolescence is characterized by later sleep onset and wake times, indicating a shift to an evening chronotype. Genome-wide association studies (GWAS) in adults show chronotype is polygenic and causally linked to depression, schizophrenia, and cognitive function. Yet, the impact of genetics on adolescent chronotype remains largely unexplored, and biological factors influencing the predictive relationship between genetics and chronotype have not been well-defined. This study aims to assess the utility of polygenic scores (PGS) derived from adult GWAS in predicting adolescent chronotype, mental health, and cognition while considering sex- and puberty-dependent effects. METHODS: Generalized linear models were used to assess the relationship between PGS for chronotype and self-reported chronotype, mental health, and cognition in 2411 youths of European ancestry aged 10-13 years. Interaction terms assessed whether the genotype-phenotype relationships varied by sex or pubertal development. Statistical significance was determined using a likelihood ratio test. RESULTS: Significant sex- and puberty-dependent effects were observed. Higher PGS for morningness concordantly predicted earlier self-reported chronotype, but in female youth only. Follow-up analyses showed that sex-specific effects were mediated by the interaction between PGS and pubertal status. Greater genetic predisposition for morningness was negatively associated with somnolence and cognition in males and negatively associated with psychotic-like experiences in females. CONCLUSIONS: The influence of genetic predisposition for early versus late chronotype on adolescent sleep-wake behavior emerges as puberty progresses. These findings suggest puberty is a critical transition when genetic variants associated with chronotype in adults become relevant to pediatric cohorts.

Humans↗
PubMed2026

Causal Effects of Gut Microbiota on Morning Chronotype, Insomnia and Sleep Duration: A Two-Sample Mendelian Randomization Study.

BACKGROUND: The gut microbiota has been shown to be closely associated with brain function; however, whether it exerts a causal influence on sleep traits remains to be further explored. Mendelian randomization (MR) is an emerging epidemiological approach that uses whole-genome sequencing data to infer causal relationships. In this study, we conducted a two-sample MR analysis to investigate the causal effects of gut microbiota on three domains of sleep traits: morning chronotype, insomnia, and sleep duration. METHODS: Single nucleotide polymorphisms strongly associated with 196 gut microbiota taxa were selected as instrumental variables. Morning chronotype, insomnia, and sleep duration were used as outcomes. MR and sensitivity analyses were performed to assess the causal relationships between gut microbiota and sleep traits. RESULTS: Three taxa (Bifidobacteriales, Bifidobacteriaceae, and Bifidobacterium) were negatively associated with morning chronotype, while Tyzzerella 3 showed a positive causal effect on morning chronotype. Oscillibacter was negatively associated with insomnia, whereas four taxa (Negativicutes, Selenomonadales, the Clostridium innocuum group, and Lachnoclostridium) were identified as risk-increasing factors for insomnia. Lentisphaerae and Victivallaceae were positively associated with sleep duration. Actinobacteria and Alistipes had negative effects on long sleep duration, whereas Ruminiclostridium 6 was positively associated with long sleep duration. Four taxa (Victivallales, Anaerofilum, Lentisphaerae, and Lentisphaeria) were negatively associated with short sleep duration. CONCLUSIONS: Our findings suggest that specific gut microbiota taxa may be positively or negatively associated with sleep traits. These results offer new insights into the potential role of gut microbiota in sleep regulation and provide a basis for future studies aimed at understanding whether modulating microbial composition could influence sleep health.

Mendelian randomization↗
PubMed2018

Chronotype and cellular circadian rhythms predict the clinical response to lithium maintenance treatment in patients with bipolar disorder.

Bipolar disorder (BD) is a serious mood disorder associated with circadian rhythm abnormalities. Risk for BD is genetically encoded and overlaps with systems that maintain circadian rhythms. Lithium is an effective mood stabilizer treatment for BD, but only a minority of patients fully respond to monotherapy. Presently, we hypothesized that lithium-responsive BD patients (Li-R) would show characteristic differences in chronotype and cellular circadian rhythms compared to lithium non-responders (Li-NR). Selecting patients from a prospective, multi-center, clinical trial of lithium monotherapy, we examined morning vs. evening preference (chronotype) as a dimension of circadian rhythm function in 193 Li-R and Li-NR BD patients. From a subset of 59 patient&#xa0;donors, we measured circadian rhythms in skin&#xa0;fibroblasts longitudinally over 5 days using a bioluminescent reporter (Per2-luc). We then estimated circadian rhythm parameters (amplitude, period, phase) and the pharmacological effects of lithium on rhythms in cells from Li-R and Li-NR donors. Compared to Li-NRs, Li-Rs showed a difference in chronotype, with higher levels of morningness. Evening chronotype was associated with increased mood symptoms at baseline, including depression, mania, and insomnia. Cells from Li-Rs were more likely to exhibit a short circadian period, a linear relationship between period and phase, and period shortening effects of lithium. Common genetic variation in the IP3 signaling pathway may account for some of the individual differences in the effects of lithium on cellular rhythms. We conclude that circadian rhythms may influence response to lithium in maintenance treatment of BD.

Adult↗
PubMed1975

Chronotypic action of theophylline and of pentobarbital as circadian zeitgebers in the rat.

In the rat the deep body temperature rhythm, monitored by telemetry, can be reset in a predictable direction by a stimulant (theopylline) and by a depressant (pentobarbital). When the drugs are applied immediately before or during the early active phases of the circadian cycle, the rhythm is set back (phase delay). When applied later, past the thermal peak, theophylline, but not pentobarbital, shifts the rhythm ahead (phase advance). Theophylline and pentobarbital in addition to having a number of already established pharmacological properties are now further identified as chronobiotics: they are drugs that may be used to alter the biological time structure by rephasing a circadian rhythm.

Animals↗
PubMed2025

Genetic analysis of Schistosoma mansoni in a low-transmission area in Brazil suggests population sharing between wild-hosts and humans and geographical isolation.

BACKGROUND: The fluke Schistosoma mansoni is the causative agent of intestinal schistosomiasis, a neglected tropical disease, and remains prevalent in certain regions of Brazil. In the municipality of Sumidouro, state of Rio de Janeiro, Brazil, a low-endemic area for S. mansoni, water rats (Nectomys squamipes) are naturally infected by this trematode. The S. mansoni populations infecting humans and water-rats in Sumidouro exhibit distinct patterns of cercarial emergence (chronotypes) and phenotypic differences between hosts. Previous studies have shown that the adaptation of S. mansoni populations to human hosts (diurnal chronotype) and water rats (nocturnal chronotype) could result in prezygotic isolation. To test this hypothesis, we employed the mitochondrial cytochrome c oxidase subunit 1 gene (MT-CO1) and microsatellite loci as genetic markers. PRINCIPAL FINDINGS: We assessed the population structure between the definitive host species and geographically distant isolates collected from two endemic localities (Pamparr&#xe3;o-PAM and Encanto-Soledade-ENC-SOL) in Sumidouro. Additionally, we evaluated the phylogenetic relationships between S. mansoni from Sumidouro and those from other countries. Five haplotypes of the MT-CO1 gene were identified, with haplotypes 3 and 4 exclusive to ENC-SOL, and haplotypes 1, 2, and 3 were shared between humans and water rats. Haplotype 1 was also shared with other Brazilian localities, South American countries and a single locality in West Africa. The remaining haplotypes were exclusive to Sumidouro, indicating local genetic diversity. Population structure analysis revealed no genetic differentiation associated with host species but rather geographical structuring, probably due to the sedentary habits of rodents and the limited movement of humans between localities. This finding indicates that S. mansoni populations with different chronotypes are not genetically isolated and that significant gene flow occurs between them. CONCLUSIONS: In conclusion, our findings confirm that wild rodents contribute to the maintenance of the S. mansoni life cycle in Sumidouro and can serve as indicators of local transmission hotspots.

Animals↗
PubMed2026

Genetic Association Between Sleep Traits and Vertigo Risk: A Two-sample Bidirectional Mendelian Randomization Study.

BACKGROUND: Observational studies suggest the potential association between sleep traits and vertigo; however, causal evidence remains limited. OBJECTIVE: This study aimed to explore the relationship between genetically predicted sleep traits and vertigo with the Mendelian randomization (MR) method. METHODS: Instrumental variables for sleep traits (snoring, sleep duration, insomnia, daytime sleepiness, daytime napping, and chronotype) were adopted from genomewide association studies (GWAS) data of European ancestry from UK Biobank. The summary-level datasets of vertigo were retrieved from the GWAS of FinnGen. Inversevariance weighted (IVW) method was adopted as the main analysis. RESULTS: IVW analysis revealed a significant association between genetically predicted daytime napping (OR = 1.51, 95% CI =1.08-2.12, P = 0.016) and chronotype (OR = 1.13, 95% CI =1.01-1.26, P = 0.033), both of which were associated with an increased risk of vertigo. However, we did not find evidence for a causal effect of snoring, overall sleep duration, long sleep duration, short sleep duration, insomnia, and excessive daytime sleepiness on vertigo. No reverse causality was detected. CONCLUSION: Our findings suggest that abnormal sleep patterns may serve as risk factors for vertigo disorders and offer opportunities for the prevention and management of vertigo disorders.

Humans↗
PubMed2026

"Out of sync and overlooked" - Relationship between social jetlag and anxiety in adolescents: Systematic review and meta-analysis.

Anxiety is the most prevalent mental health difficulty in adolescence, a period characterised by a shift towards an eveningness chronotype that is not aligned with societal demands (i.e., school start times). Experiencing "social jetlag" (SJL), a discrepancy in weekday-weekend sleep timing, is proposed to be associated with increased anxiety. A PRISMA-compliant systematic review and meta-analysis was conducted to investigate the relationship between SJL and anxiety in adolescents (age range: 12-18 years). Systematic searches were conducted in PsycINFO, Web of Science, Embase, PubMed, MEDLINE, and ProQuest Dissertations & Theses Global on 14th November 2024 to retrieve empirical studies analysing the relationship between SJL and anxiety in 12-18-year-olds. A multi-level random-effect meta-analysis was conducted in R to estimate the magnitude of the association between SJL and anxiety. After screening 2,138 records, 18 studies were included in the systematic review, with 12 included in the meta-analysis (235,526 participants in total) and six in a narrative review. A small association was found between increased SJL and more severe anxiety (Fisher's z&#x202f;=&#x202f;0.0614, 95% CI [0.0268, 0.0961], p&#x202f;=&#x202f;0.0011). These findings highlight the importance of addressing behavioural strategies targeting healthy regular sleep as a tool to improve mental health in adolescence.

Adolescent↗
PubMed1989

Sleep disorder symptoms among nurses and nursing aides.

Nurses and nursing aides (n = 418) currently working on a regular evening or day schedule were compared in terms of sleep disorder symptoms. The relationship between past nightwork and sleep disorder symptoms was also assessed. The prevalence of individual symptoms varied from 6 to 53%. Evening workers showed a pattern of sleep disorder compatible with sleep deprivation, whereas the pattern for day workers was more compatible with insomnia. Past nightwork was significantly associated with symptoms of day tiredness and the quantity of sleep obtained was influenced by past nightwork. The prevalence of a combination of four insomnia symptoms (initial, intermittent, and terminal insomnia and fatigue during the day) was 5.4% among current day workers but no cases were identified among evening workers. Among day workers, the trend for insomnia across levels of duration of past nightwork fell slightly short of conventional statistical significance (P = 0.09). The relationship between a combination of four symptoms was neither modified nor confounded by variables such as age, chronotype, intensity of past nightwork, and latency. In conclusion, although some sleep symptoms were associated with nightwork, a clear residual effect on a combination of symptoms could not be shown.

Adult↗
PubMedDate not supplied

A behavioural method for accelerating re-entrainment of rhythms to new light-dark cycles.

The idea of ameliorating jetlag with drugs has received considerable attention. Melatonin has been found to reduce feelings of jetlag in people after transatlantic flights. In hamsters, injections of triazolam, a benzodiazepine, increase the rate of adjustment of activity rhythms to an 8 h advance of the light-dark (LD) cycle. But melatonin can make people drowsy and triazolam often induces hamsters to run in their wheels. Therefore, it is not clear whether these chemicals exert their chronotypic effects by acting directly on circadian pacemakers or because they first alter behavioural states. Non-photic behavioural events (for instance, social interactions) are capable of entraining rhythms and causing phase shifts. Thus, it is possible that behavioural events alone could alter the rate of adjustment to new LD cycles. To investigate this possibility, we studied the rate of re-entrainment of hamsters in a testing paradigm similar to that used with triazolam. We found that the rate of adjustment could be more than doubled simply by making the animals active on a single occasion in the middle of their normal rest period, immediately after the shift in the LD cycle.

Acclimatization↗
PubMed2026

Differences in circadian rhythm changes between myopic and non-myopic college students over 2&#x2009;years.

This study aimed to characterize and compare the differences in circadian rhythm changes during 2&#x2009;years between college students with myopia and non-myopia based on a longitudinal cohort study. Wake-up time and bedtime were obtained through a self-administered questionnaire. Chronotype was assessed using the reduced Morningness-Eveningness Questionnaire (rMEQ). Circadian rhythm timing was determined by dim-light melatonin onset (DLMO), measured through hourly saliva collection from 21:00 to 01:00. A total of 450 college students (146 [32.4%] males) with a mean age of 18.65&#x2009;&#xb1;&#x2009;1.05&#x2009;years were included, of whom 353 (78.4%) students had myopia. Compared with non-myopic individuals, myopic students slept later, woke up earlier, and exhibited lower rMEQ scores at baseline. Over the 2-year follow-up, both groups showed significantly earlier bedtimes, later wake-up times, and higher rMEQ scores. Only myopic students demonstrated a 45-minute delay in DLMO after the 2-year follow-up. After adjusting for potential confounders, linear mixed-effects models showed that myopic individuals had later bedtimes and earlier wake-up times. These findings indicate significant circadian rhythm changes in individuals with myopia, suggesting the potential of targeted sleep rhythm interventions on preventing myopia.

Myopia↗
PubMed2026

Diet and sleep among college student populations: a systematic review.

College students are at-risk for both poor diet and poor sleep. We aimed to systematically review the evidence regarding associations between diet and sleep health within this population. A comprehensive electronic search was conducted in PubMed, Embase, Scopus, Web of Science, and PsycINFO from the earliest possible date through February 6, 2026. A total of 57 studies representing 44 countries were retained; most were cross-sectional. There were 22 studies that examined dietary patterns in relation to sleep, generally showing that healthier diet patterns, including the Mediterranean Diet, were related to better sleep quality. Among 20 studies that examined individual foods or nutrients, there was evidence that fruits, vegetables, dairy, protein, and lower intake of sugar-sweetened beverages were linked to better sleep health, although some findings were mixed. Finally, 15 studies related meal timing to sleep quality, showing that breakfast skipping and later last meals were associated with poor sleep health. Overall, these studies reveal robust cross-sectional associations between diet and sleep among college students, but more longitudinal studies and randomized controlled trials are needed to evaluate directionality. Moreover, a key direction for future study is consideration of sleep and nutrition situated within the unique contexts of college settings and academic schedules.

Humans↗