Circadian typology: a comprehensive review

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

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

Chrono-tailored drug delivery systems: recent advances and future directions

Circadian rhythms influence a range of biological processes within the body, with the central clock or suprachiasmatic nucleus (SCN) in the brain synchronising peripheral clocks around the body. These clocks are regulated by external cues, the most influential being the light/dark cycle, in order to synchronise with the external day. Chrono-tailored or circadian drug delivery systems (DDS) aim to optimise drug delivery by releasing drugs at specific times of day to align with circadian rhythms within the body. Although this approach is still relatively new, it has the potential to enhance drug efficacy, minimise side effects, and improve patient compliance. Chrono-tailored DDS have been explored and implemented in various conditions, including asthma, hypertension, and cancer. This review aims to introduce the biology of circadian rhythms and provide an overview of the current research on chrono-tailored DDS, with a particular focus on immunological applications and vaccination. Finally, we draw on some of the key challenges which need to be overcome for chrono-tailored DDS before they can be translated to more widespread use in clinical practice.

Chronotype and metabolic syndrome in midlife: findings from the Northern Finland Birth Cohort 1966

Evening chronotype is known to be associated with various chronic diseases and cardiovascular risk factors. Metabolic syndrome is a group of conditions that together raise the risk of coronary heart disease, diabetes, stroke, and other serious health problems. Only a few studies have been published on the association between chronotype and metabolic syndrome in unselected population data, with conflicting results. The aim of this study was to evaluate the association between chronotype and metabolic syndrome at population level by using unselected Northern Finland Birth cohort 1966 (NFBC1966) database. The study population consists of participants with NFBC66 (n = 5,113, 57% female) at the age of 46 yr old. Chronotype was determined with shortened Morningness-Eveningness Questionnaires and expressed as morning (44%), intermediate (44%), and evening types (12%). Metabolic syndrome was determined according to the definition of International Diabetes Federation. One-way ANOVA, Kruskal-Walli's test, and χ2 tests were used to compare the chronotype groups, followed by logistic regression analysis (adjusted with alcohol consumption, smoking, marital status, level of education, and leisure-time physical activity). In women, the prevalence of metabolic syndrome was statistically significantly higher in the evening type group: 23, 24, and 34% for morning, intermediate, and evening groups, respectively (P < 0.001). In logistic regression analysis, evening chronotype was associated with higher risk of having metabolic syndrome (OR 1.5; CI 95% 1.2 to 2.0). In this population-based birth cohort study, the evening chronotype was independently associated with higher prevalence of metabolic syndrome in women.NEW & NOTEWORTHY Only a few studies have been conducted on the association between chronotype and metabolic syndrome in unselected population data, with conflicting results. In this population-based cohort study of 5,113 participants, the evening chronotype associated with metabolic syndrome in women when there was no such association in men. The result supports a previous South Korean population study of 1,620 participants, in which the association was also found in women, but not in men.

Sleep quality mediates the association between chronotype and mental health in young Indian adults

There is increasing recognition of 'higher preference for eveningness' as a potential independent risk factor for poor mental health. To examine the chronotype-mental health relationship while also quantifying the potential roles of poor sleep quality, relevant personality traits, and childhood trauma, we assessed 282 young adults (18-40 years; 195 females) residing in North India, between January and March 2023 (to control for seasonal variation), using self-report measures of diurnal preference, sleep patterns, mental health (depression, anxiety, and stress), personality traits (extraversion, neuroticism, schizotypy, and impulsivity), and childhood trauma. The results showed a significant association between eveningness and poor mental health but this association was fully mediated by poor sleep quality. Neuroticism, emotional abuse and cognitive disorganisation were correlated with eveningness as well as with poor mental health and sleep quality. Neuroticism and emotional abuse, but not cognitive disorganisation, also had indirect effects on mental health via sleep quality. Our findings highlight the crucial role played by sleep quality in the chronotype-mental health relationship.

Validation of the French version of the Munich ChronoType questionnaire and associations between chronotype and physiological parameters

Assessing chronotype is essential in clinical and research environments, but the Munich ChronoType Questionnaire (MCTQ), a widely utilised tool, is not available in French. Therefore, we carried out an observational monocentric study to validate the French MCTQ against the sleep diary for sleep schedules, the Morningness-Eveningness Questionnaire (MEQ) for chronotype, and polysomnography measures. We utilised the mid-sleep point on free days (MSF), adjusted for sleep debt (MSFsc), to gauge morningness/eveningness. The study included 80 participants (average age: 40.9 years, 50% female). The sleep schedules determined by the MCTQ and the sleep diary showed a high correlation. The MSFsc demonstrated a significant correlation with the MEQ, persisting even under sleep constraints such as an alarm on free days. The predictive accuracy was strong for a morning chronotype and moderate for an evening chronotype as assessed using the MEQ. In summary, the French MCTQ is a reliable tool for researchers and clinicians for assessing sleep schedules and chronotype in French-speaking populations. The MSFsc can effectively predict chronotype, even under sleep constraints. However, for the evening chronotype, self-assessment appears to be more accurate. The association with polysomnography measures enriches our understanding of the chronotype at the intersection of behaviour and physiology.

Sleep quality according to chronotype in nurses working 8-hour shifts

BACKGROUND

To date, studies have been focused on sleep disturbances of nurses working during night shifts. There is a lack of understanding regarding the sleep quality of nurses working in the rapid rotation system for each type of shift work.

AIMS

To determine the relationship between chronotype and sleep quality according to shift type (i.e. day, evening and night shifts) in nurses working 8-hour rotating shifts.

METHODS

A cross-sectional, descriptive study was conducted from two tertiary hospitals in South Korea from December 2021 to September 2022, including nurses working 8-hour rotating shifts (N = 74). They completed questionnaires to measure general, occupational and sleep-related characteristics, chronotype, insomnia severity and daytime sleepiness. Additionally, sleep parameters were collected from actigraphy and sleep diaries for 7 days.

RESULTS

A total of 64% of nurses had an evening chronotype and 37% of nurses had an intermediate chronotype. Nurses had significantly less total sleep time and worsened sleep latency and efficiency during the day shift compared to other shift types. Compared to nurses with an intermediate chronotype, those with an evening chronotype had poorer sleep quality during day shift work.

CONCLUSIONS

Strategies to enhance nurses' sleep quality during day shifts should consider a two-level approach: individual approaches, such as improving sleep hygiene, and administrative approaches, such as establishing a chronotype-based shift system for scheduling.

Comparison of Chronotypes and their Relationship with Academic Performance and Quality of Life in University Students

Objective  An individual's chronotype affects circadian characteristics associated with bedtime, waking, and other daily activities. It is known that academic achievement is strongly dependent on personality traits. The present study aimed to investigate the relationship regarding chronotype, quality of life, and academic performance of university students by comparing three educational fields: medicine, technology, and art. Materials and Methods  The present cross-sectional study was conducted with 400 medicine, technology, and art students enrolled at universities in Tehran between2018 and 2019, with convenience sampling from January 2020 to January 2021. The students filled out online questionnaires, including a demographics questionnaire, a quality of life assessment questionnaire (the World Health Organization Quality of Life: Brief Version, WHOQOL-BREF), the Morningness-Eveningness Questionnaire (MEQ), the Pittsburgh Sleep Quality Index (PSQI), and the Depression, Anxiety, and Stress Scale-21 items (DASS-21). The statistical analysis was performed using the IBM SPSS Statistics for Windows software, version 22.0 ( p  < 0.05). Results  A total of 400 students were enrolled in the present study, including 115 medicine, 153 technology, and 132 art students (67.3% of female and 33.7% of male subjects, with a mean age of 21.06 ± 2.063 years). In spite of the absence of significant differences among the chronotypes of the three groups, there was a significant correlation regarding the chronotypes in all groups and quality of life ( p  = 0.005). Morning-type individuals presented better quality of life and better quality of sleep ( p  < 0.001; r = 0.175). No significant associations were found involving the students' academic performance and their chronotypes ( p  > 0.05; r = 0.026). Conclusion  Considering the chronotype's effect of improving the quality of life of students and, therefore, their academic performance, more studies are essential to effectively improve the academic performance of individuals with different chronotypes.

Eveningness chronotype influences social functioning by deteriorating depressive symptoms in remitted patients with schizophrenia

Sleep and circadian rhythm disruption (SCRD) is common in schizophrenia patients, who also typically experience impaired social functioning. While various factors influence social functioning in schizophrenia, the specific impact of sleep and circadian rhythm disruption remains unclear. This study aimed to investigate the connection between chronotype and social functioning in remitted schizophrenia patients, examining the mediating roles of depression and sleep quality. The study included 185 patients diagnosed with schizophrenia based on DSM-5 criteria. After categorizing the patients into morningness, eveningness, or intermediate chronotypes using the Morningness-Eveningness Questionnaire(MEQ), they were assessed with the Positive and Negative Syndrome Scale(PANSS), Calgary Depression Scale for Schizophrenia(CDSS), Personal and Social Performance Scale(PSPS) and Pittsburgh Sleep Quality Index(PSQI). The eveningness chronotype group showed higher CDSS and PSQI scores and lower PWBS and PSPS-Total scores than the other groups (p < 0.05). A hierarchical linear regression model assessed MEQ, PSQI, and CDSS scores' effects on PSPS total scores. MEQ scores' significance diminished when CDSS scores were included. Eveningness chronotype, particularly with increased depressive symptoms, negatively impacts social functioning in remitted schizophrenia patients.These findings contribute to the understudied area of chronotype in schizophrenia and its impact on social functioning, including its interaction with sleep..

Examining the Effects of Strength Training with Load Progression on Sleep Parameters and Mental Health in College Students

Objective  To compare the effects of strength training with load progression after 4 weeks on sleep parameters and mental health in college students. Methods  A total of 17 university students (11 women, 6 men), ranging from 18 to 21 years old, were randomized into a strength training group (STG) and a control group (CG). The Pittsburgh sleep quality index (PSQI), insomnia severity questionnaire, hospital anxiety and depression (HAD) scale, profile of mood states (POMS), and chronotype were used to evaluate the main outcomes. Training consisted of 60 minute·d -1 (2 times/week, for 4-weeks), with 3 sets of 10 to 12 repetitions, and a 1-minute rest interval between sets and exercises. Baseline and postintervention differences were analyzed using generalized estimating equations (GEE). Results  After 4 weeks of ST, a significant time effect on the chronotype (β: 1.33; p  < 0.05) was observed in the STG. Additionally, there was a significant time and group effect in the reduction of tension (β: 5.00; p  < 0.05), depression (β: 15.41; p  < 0.05), anger (β: 8.00; p  < 0.05), and confusion (β: 6.50; p  < 0.05). For fatigue (β: 2.66; p  < 0.05), there was a significant time effect difference in its reduction. Vigor was meaningfully increased in the STG group (β: -1.75; p  < 0.05). Furthermore, a significant positive relationship was observed between sleep quality and anxiety (r = 0.54; p  = 0.03). Finally, insomnia was positively related with an increase in confusion (r = 0.70; p  = 0.04) and anxiety (r = 0.52; p  = 0.04), as well as with a decrease in vigor (r = -0.71; p  = 0.03). Discussion  Short-term strength training for 4 weeks was effective for improving mental health, helping achieve characteristics of a positive mood profile, that is, low values for negative factors and a high value for the positive factor.

Why circadian rhythmicity matters: associations between sleep irregularity and mental health conditions during the Covid-19 health crisis

OBJECTIVE

To assess the association between sleep irregularity, anxiety, and depression while controlling for other sleep dimensions and using a longitudinal design.

METHODS

Longitudinal cohort study which started in April 2020 during the first French lockdown in the general population. Follow-up questionnaires were completed in June 2020, a period without lockdown measures. Participants were asked about their sleep (regularity, duration, timing, complaints) and their anxiety (General Anxiety Disorder-7) and depressive (Patient Health Questionnaire-9) symptoms.

RESULTS

A total of 3745 participants were included (mean age: 28.9 years) with 2945 women (78.6%). At baseline, 38.1% (1428) of participants reported irregular sleep timing, 23.8% (891) anxiety and 28.9% (1081) depressive symptoms. In cross-sectional analyses, irregular sleep timing was associated with a 2.5-fold higher likelihood of anxiety and a 4-fold higher likelihood of depressive symptoms compared to regular sleepers. Associations were not explained by the other sleep dimensions and persisted in a longitudinal analysis, with irregular sleep timing at baseline being associated with anxiety (OR = 3.27[1.58-6.76]) and depressive symptoms (OR = 3.45[1.66-7.19]) during follow-up.

CONCLUSION

The results show a strong association between sleep irregularity and mental health. Furthers studies are needed to explore how sleep regularity could promote good mental health in non-clinical populations.

Domiciliary monitoring of exhaled nitric oxide in the management of asthma: a pilot study

BACKGROUND

Whether asthma patients could benefit from home monitoring for fractional exhaled nitric oxide (flow of 50 mL/s, FeNO50) is unknown. We explore the application value of home monitoring FeNO50 in daily asthma management.

METHODS

Twenty-two untreated, uncontrolled asthma patients were selected. Medical history, blood and sputum samples, pulmonary function, Asthma Control Test (ACT), and other clinical data of the subjects were collected. All subjects underwent daily monitoring for four weeks using a FeNO50 monitor and mobile spirometry (mSpirometry). The diurnal differences and dynamic changes were described. Compare the effect-acting time and the relative plateau of treatment between FeNO50 and mSpirometry monitoring.

RESULTS

In the first two weeks, the morning median (IQR) level of FeNO50 was 44 (35, 56) ppb, which was significantly higher than the evening median level [41 (32, 53) ppb, P = 0.028]. The median (IQR) effect-acting time assessed by FeNO50 was 4 (3, 5) days, which was significantly earlier than each measure of mSpirometry (P < 0.05). FeNO50 reached the relative plateau significantly earlier than FEV1 (15 ± 2 days vs. 21 ± 3 days, P < 0.001). After treatment, the daily and weekly variation rates of FeNO50 showed a gradually decreasing trend (P < 0.05). The ACT score, sputum eosinophils, and blood eosinophils also significantly improved (P ≤ 0.01).

CONCLUSIONS

The daily home monitoring of FeNO50 in asthmatic patients showed significant circadian rhythm, and the sensitivity of FeNO50 in evaluating the response to treatment was higher than mSpirometry. The daily and weekly variation rates of FeNO50 change dynamically with time, which may be used to assess the condition of asthma.

Depression, Anxiety and Poor Sleep Quality are Associated with Chronotype and Financial Wellness in University Students

Background: Evidence suggests the importance of a person's chronotype in predicting various aspects of an individual's physical and mental health. While the effect of depression on sleep is well established, the impact of a person's specific sleep timing and chronotype on the prevalence of both depression and anxiety has yet to be fully understood, especially among university students, vulnerable to mental health problems. In addition, other factors also seem to influence the occurrence of depression and anxiety among students as well as their quality of sleep, one of which being the students' financial wellness. The objective was to evaluate the association between chronotype and the severity and prevalence of depression among Lebanese university students, while also taking into account the possible connection between chronotype and financial wellness and both anxiety and sleep quality. Methods: This cross-sectional study was conducted between December 2021 and February 2022; 330 Lebanese university students was included (mean age 21.75 ± 2.43; 67.3% females). Results: The majority of the Lebanese university students in our sample were found to have an intermediate typology (63.0%), followed by the evening typology, which appeared to constitute 28.2% of the sample, while only 8.8% possessed a morning typology. In this study, having an intermediate or evening typology compared to a morning one was significantly associated with higher depression and worse sleep quality. In addition, having an evening chronotype compared to a morningness propensity was significantly associated with more anxiety. Conclusion: This study found a positive association between an evening typology (chronotype) and higher depression and anxiety and poorer quality of sleep. Although preliminary and based on cross-sectional data, this research could help provide a better understanding of the different chronotypes among university students, and of the possible increased susceptibility of some of these typologies (i.e., evening-type) to mental health problems.

Psychometric properties of the Turkish reduced morningness and eveningness questionnaire

The aim of this study was to examine the psychometric properties of the 5-item Turkish Reduced Morningness-Eveningness Questionnaire (rMEQ) for the first time. The study involved 875 university students in an adaptation and validation study. Participants completed the rMEQ, MEQ, Depression Anxiety Stress Scale-21 (DASS-21), Insomnia Severity Index (ISI), Barratt Impulsiveness Scale Short Form (BIS-SF), and Oxford Happiness Questionnaire Short Form (OHQ-SF). The factor structure, convergent validity, internal consistency, sensitivity, and specificity of the rMEQ were examined. The confirmatory factor analysis showed that the rMEQ had a one-dimensional structure with good fit indices (χ2/df = 2.94, CFI = 0.990, TLI = 0.979, RMSEA = 0.047, and SRMR = 0.019). There was a significantly strong correlation between rMEQ and MEQ. In addition, we found a significantly weak correlation between rMEQ and DASS-21, ISI, BIS-SF, and OHQ-SF. The internal consistency coefficients of rMEQ were Cronbach's α = 0.706 and McDonald's ω = 0.740. The sensitivity and specificity of rMEQ were 83.3%-92.7% for morning types and 86.3%-87.3% for evening types. The Turkish rMEQ has adequate psychometric properties and can be used to assess an individual's chronotype.

The relationship between the morningness-eveningness questionnaire and incident cancer: A historical clinical cohort study

OBJECTIVE

We conducted a retrospective cohort study to explore the relationship between chronotype measured by the total Morningness-Eveningness Questionnaire (MEQ) score and incident cancer.

METHODS

We used clinical and provincial health administrative data on consecutive adults who underwent a Level 1 Polysomnography (PSG) and completed the MEQ between 2010 and 2015 in an academic hospital (Ontario, Canada) and were cancer-free at baseline. Cancer status was derived from the Ontario Cancer Registry. Individuals were followed until death or March 31, 2020. We used multivariable Cox cause-specific regressions to address the research objective.

RESULTS

Of 3,004 individuals, 1,781 were analyzed: a median age of 54 years (IQR: 40-64) and 838 (47.1%) men. The median total MEQ score was 63 (IQR: 55-69); 61 (3.4%) were classified as evening (≤41), 536 (30.1%) as intermediate (42-58), and 1,184 (66.5%) as morning chronotypes (≥59). Over a median of 7 years (IQR: 5-8), 120 (6.7%) developed cancer. A U-shape relationship was found between the total MEQ score and an increased hazard of incident cancer, controlling for PSG measures of sleep apnea severity and sleep architecture, demographics, and comorbidities. Compared to the median of 63.0, a total MEQ score greater or less than the median was associated with an increased hazard of incident cancer, with the largest effect for those with a total score ≥76 (e.g., HR of a MEQ total score of 78 vs. 63: 2.01, 95% CI: 1.09-3.71).

CONCLUSION

The U-shaped curve may reflect deviations from a standard circadian tendency, which may stress biological systems and influence malignancy risk.

Chronotype changes after sex hormone use: A prospective cohort study in transgender users of gender-affirming hormones

Chronotype, an individual's preferred sleep-wake timing, is influenced by sex and age. Men sometimes report a later chronotype than women and older age is associated with earlier chronotype. The sex-related changes in chronotype coincide with puberty and menopause. However, the effects of sex hormones on human chronotype remain unclear. To examine the impact of 3 months of gender-affirming hormone therapy (GAHT) on chronotype in transgender persons, this study used data from 93 participants from the prospective RESTED cohort, including 49 transmasculine (TM) participants starting testosterone and 44 transfeminine (TF) participants starting estrogens and antiandrogens. Midpoint of sleep and sleep duration were measured using the ultra-short Munich ChronoType Questionnaire (µMCTQ). After 3 months of GAHT, TM participants' midpoint of sleep increased by 24 minutes (95% CI: 3 to 45), whereas TF participants' midpoint of sleep decreased by 21 minutes (95% CI: -38 to -4). Total sleep duration did not change significantly in either group. This study provides the first prospective assessment of sex hormone use and chronotype in transgender persons, showing that GAHT can change chronotype in line with cisgender sex differences. These findings provide a basis for future studies on biological mechanisms and clinical consequences of chronotype changes.

External validity of the reduced Morningness-Eveningness Questionnaire for Children and Adolescents: an actigraphic study

The aim of this study was to examine the external validity of the reduced Morningness-Eveningness Questionnaires for Children and Adolescents, using circadian motor activity, assessed through actigraphy, as an external criterion. Overall, 458 participants (269 females), with a mean (standard deviation) age of 15.75 (1.16) years, took part in this study. Each adolescent was requested to wear the actigraph Micro Motionlogger Watch actigraph (Ambulatory Monitoring, Inc., Ardlsey, NY, USA) around the non-dominant wrist for 1 week. At the end of the actigraphic recording, participants completed the reduced Morningness-Eveningness Questionnaires for Children and Adolescents. We extracted the motor activity counts, minute-by-minute over the 24 h, to depict the 24-h motor activity pattern, and we adopted the statistical framework of functional linear modelling to examine its changes according to chronotype. According to the reduced Morningness-Eveningness Questionnaires for Children and Adolescents cut-off scores, 13.97% of participants (n = 64) belonged to the evening-types category, 9.39% (n = 43) to morning-types, while the remaining (76.64%, n = 351) to the intermediate-types category. Evening types moved significantly more than the intermediate and morning types from around 10:00 p.m. to 2:00 a.m., while the opposite pattern of results was observed around 4:00 a.m. The results highlighted a significant difference in the 24-h motor activity pattern between chronotypes, in line with the expectations based on their well-known behaviour. Therefore, this study shows that the external validity of the reduced Morningness-Eveningness Questionnaire for Children and Adolescents, established by considering motor activity (recorded through actigraphy) as an external criterion, is satisfactory.

Shift schedules and circadian preferences: the association with sleep and mood

Object

We explored the circadian preferences of non-shift workers (non-SWs) and various types of shift workers (SWs), and the associations of these preferences with sleep and mood.

Methods

In total, 4,561 SWs (2,419 women and 2,142 men aged 37.00 ± 9.80 years) and 2,093 non-SWs (1,094 women and 999 men aged 37.80 ± 9.73 years) completed an online survey. Of all SWs, 2,415 (1,079 women and 1,336 men aged 37.77 ± 9.96 years) reported regularly rotating or fixed schedules ("regular SWs"), and 2,146 (1,340 women and 806 men aged 36.12 ± 9.64 years) had irregular schedules ("irregular SWs"). Of the regular SWs, 2,040 had regularly rotating schedules, 212 had fixed evening schedules, and 163 had fixed night schedules. All participants completed the Morningness-Eveningness Questionnaire (MEQ) exploring circadian preferences, the short form of the Center for Epidemiological Studies-Depression Scale (CES-D) evaluating depression, the Insomnia Severity Index (ISI), and the Epworth Sleepiness Scale (ESS).

Results

Compared to non-SWs, SWs had lower MEQ scores, i.e., more eveningness, after controlling for age, gender, income, occupation, and weekly work hours (F = 87.97, p < 0.001). Irregular SWs had lower MEQ scores than regular SWs (F = 50.89, p < 0.001). Among regular SWs, the MEQ scores of fixed evening and fixed night SWs were lower than those of regularly rotating SWs (F = 22.42, p < 0.001). An association between the MEQ and ESS scores was apparent in non-SWs (r = -0.85, p < 0.001) but not in SWs (r = 0.001, p = 0.92).

Conclusion

SWs exhibited more eveningness than non-SWs; eveningness was particularly prominent in SWs with irregular or fixed evening/night shifts. Eveningness was associated with sleepiness only in non-SWs, but not in SWs.

Effect of circadian rhythm and menstrual cycle on physical performance in women: a systematic review

The literature has extensively investigated potential factors influencing women's performance, including the menstrual cycle and the circadian rhythm. However, review articles exploring the combined influence of both factors remain lacking in the literature. The study aimed to systematically review the literature on the relationship between the circadian rhythm and menstrual cycle on physical performance in women. The review followed the PRISMA guidelines. The search was performed on the Web of Science, PubMed, Scopus, SPORTDiscus, and Google Scholar databases. Of the 1205 records identified, four articles met the inclusion criteria. From four articles, two studies found a significant interaction between the time of day and phase of the menstrual cycle with physical performance. The isometric strength increased in the afternoon in the mid-luteal phase (versus the morning in the mid-luteal phase, p < 0.05), and the maximum cycling power was higher in the afternoon in the mid-follicular phase (versus the morning in the mid-follicular phase, p < 0.01). Our findings suggest that the time of day and the menstrual cycle phase affect physical performance, with the daytime potentially having a more significant influence. However, the results should be interpreted cautiously due to the limited studies and diverse methodologies used to monitor the menstrual cycle phase. This review reinforces the need for further investigation to understand better the combined effects of the circadian rhythm and menstrual cycle on women's physical performance.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=380965, identifier CRD42022380965.

Associations of chronotype with anxiety, depression and insomnia among general adult population: A cross-sectional study in Hubei, China

BACKGROUND

The relationship between chronotype and anxiety, depression, and insomnia was inconsistent. We aimed to assess the association between chronotype and mental health and the potential moderating effect of age and socioeconomic status (SES).

METHODS

A multi-stage sampling cross-sectional study with 12,544 adults was conducted. Chronotype, anxiety, depression, and insomnia were investigated by 5-item Morning and Evening, 7-item Generalized Anxiety Disorder, 9-item Patient Health, and the 7-item Insomnia Severity Index Questionnaires. Logistic regression was conducted.

RESULTS

The predominant chronotype was morning chronotype (69.2 %), followed by 27.6 % intermediate and 3.2 % evening chronotype. The prevalence of anxiety, depression, and insomnia was 0.7 %, 1.9 %, and 9.6 %, respectively. Compared with intermediate chronotype, morning chronotype participants had a lower risk of anxiety (OR = 0.28,95%CI:0.18-0.44), depression (OR = 0.54,95%CI:0.41-0.72) and insomnia (OR = 0.67,95%CI:0.58-0.77), while evening chronotype participants had a higher risk of depression (OR = 1.98,95%CI:1.06-3.71) but not anxiety or insomnia. Interactions between chronotype with age and SES on insomnia (Pinteraction < 0.05) were found. A more profound association between morning chronotype and insomnia was observed in <65 years participants (OR = 0.59,95%CI:0.50-0.71) and those with monthly household income ≥10,000yuan (OR = 0.21,95%CI:0.12-0.35), compared with their counterparts.

LIMITATIONS

The cross-sectional design limited causal conclusions. Only adults were included; the findings could not be generalized to children.

CONCLUSIONS

The morning chronotype might be protective for anxiety, depression, and insomnia, while the evening chronotype might be a risk factor for depression. Future studies are needed to assess the efficacy of chronotype-focused intervention for mental health. Insomnia prevention efforts should pay more attention to the elderly and those with lower incomes.

Quantifying Apathy in Late-Life Depression: Unraveling Neurobehavioral Links Through Daily Activity Patterns and Brain Connectivity Analysis

BACKGROUND

Better understanding apathy in late-life depression would help improve prediction of poor prognosis of diseases such as dementia. Actimetry provides an objective and ecological measure of apathy from patients' daily motor activity. We aimed to determine whether patterns of motor activity were associated with apathy and brain connectivity in networks that underlie goal-directed behaviors.

METHODS

Resting-state functional magnetic resonance imaging and diffusion magnetic resonance imaging were collected from 38 nondemented participants with late-life depression. Apathy was evaluated using the diagnostic criteria for apathy, Apathy Evaluation Scale, and Apathy Motivation Index. Functional principal components (fPCs) of motor activity were derived from actimetry recordings taken for 72 hours. Associations between fPCs and apathy were estimated by linear regression. Subnetworks whose connectivity was significantly associated with fPCs were identified via threshold-free network-based statistics. The relationship between apathy and microstructure metrics was estimated along fibers by diffusion tensor imaging and a multicompartment model called neurite orientation dispersion and density imaging via tractometry.

RESULTS

We found 2 fPCs associated with apathy: mean diurnal activity, negatively associated with Apathy Evaluation Scale scores, and an early chronotype, negatively associated with Apathy Motivation Index scores. Mean diurnal activity was associated with increased connectivity in the default mode, cingulo-opercular, and frontoparietal networks, while chronotype was associated with a more heterogeneous connectivity pattern in the same networks. We did not find significant associations between microstructural metrics and fPCs.

CONCLUSIONS

Our findings suggest that mean diurnal activity and chronotype could provide indirect ambulatory measures of apathy in late-life depression, associated with modified functional connectivity of brain networks that underlie goal-directed behaviors.

The Japanese version of the reduced morningness-eveningness questionnaire

Circadian typology, or "morningness" and "eveningness," is generally assessed using the Morningness-Eveningness Questionnaire (MEQ), a 19-item scale that could be burdensome in large-scale surveys. To overcome this, a 5-item version known as the reduced morningness-eveningness questionnaire (rMEQ), which is sensitive to the assessment of circadian typology, was developed; however, a validated Japanese version of the rMEQ is yet to be established. This study aimed to develop and validate the Japanese version of the rMEQ. Five essential items for the rMEQ were selected from existing Japanese MEQ data (N = 2,213), and the rMEQ was compiled. We conducted a confirmatory factor analysis for the psychometric properties of the rMEQ and confirmed its robust one-factor structure for evaluating morningness-eveningness (GFI = 0.984, AGFI = 0.951, CFI = 0.935, and RMSEA = 0.091). Reliability was evaluated via internal consistency of rMEQ items using Cronbach's α and McDonald's ω, and the values were 0.618 and 0.654, respectively. The rMEQ scores strongly correlated with MEQ (ρ = 0.883, p < 0.001), and classification agreement (Morning, Neither, and Evening types) between rMEQ and MEQ was 77.6% (Cramer's V = 0.643, Weighted Cohen's κ = 0.72), confirming the validity. The Japanese rMEQ may be a valuable tool for the efficient assessment of circadian typologies.

The relationship between chronotype, psychological pain, problematic social media use, and suicidality among university students in Turkey

Chronotype has been extensively linked to various psychological outcomes, including suicide, which significantly impacts the mortality rate among young adults worldwide. Research on the extent of these links is still ongoing. This cross-sectional study aimed to explore the complex relationships between chronotype, internet addiction, problematic social media use (PSMU), psychological pain, and suicidality in a student population. A total of 571 Turkish students (65.3% female, mean age 20.3 ± 1.63 years) completed the following scales: the Suicide Probability Scale (SPS), the Mee-Bunney Psychological Pain Assessment Scale (MBPPAS), the Social Media Disorder Scale (SMDS), the Internet Addiction Test (IAT), the Morningness - Eveningness Questionnaire (MEQ), and the Hospital Anxiety and Depression Scale (HADS). The results showed that the relationship between chronotype and suicidality was partially mediated by SMDS and MBPPAS but not by anxiety, depression, or IAT. These findings suggest that psychological pain and PSMU may be important factors that contribute to suicidality in evening-type individuals. These findings have significant implications for the development of interventions aimed at reducing suicidality among evening-type individuals. By addressing the underlying factors of psychological pain and PSMU, it may be possible to mitigate the increased risk of suicidality among this population.

Associations between chronotype and physical activity and well-being in adults

Circadian rhythms influence a preference for people's time of activity and sleep time during the day and the hours of best performance. The aim of the study was to assess the associations between chronotype, physical activity, and well-being in adults aged 20-50. The chronotype, physical activity and well-being scores were determined based on the Composite Scale of Morningness (CSM) questionnaire, the International Physical Activity Questionnaire (IPAQ) and the Well-Being Index (WHO-5) questionnaire, respectively. Study data consisted of the answers of 213 respondents (including 64 men) who took part in an online survey. The Spearman rank correlation coefficient and the matrix scatter plots were used to check the correlations between the CSM score and quality of life parameters' values. General linear models (GLMs) were performed to find differences in quality-of-life parameters between different combinations of sex and chronotype. Morning types showed the highest value of well-being score (mean = 13.48) while evening types the lowest one (mean = 8.35). Evening types spent the most time sitting compared to other chronotypes. Results of this study revealed the significant effect of chronotype on well-being and physical activity among adults. These findings suggest that chronotype is an important factor that psychologists and personal trainers should take into account.

Daily Duration of Eating for Children and Adolescents: A Systematic Review and Meta-Analysis

Time-limited eating is a dietary intervention whereby eating is limited to a specific window of time during the day. The usual eating windows of adults, and how these can be manipulated for dietary interventions, is well documented. However, there is a paucity of data on eating windows of young people, the manipulation of which may be a useful intervention for reducing obesity. This paper reviewed the existing literature on the eating windows of children and adolescents, aged 5-18 years, plus clock times of first and last intakes and variations by subgroup. Two databases (Medline and Embase) were searched for eligible papers published between February 2013 and February 2023, with forward searching of the citation network of included studies on Web of Science. Articles were screened, and data extracted, in duplicate by two independent reviewers. Ten studies were included, with both observational and experimental designs. Narrative synthesis showed large variations in eating windows with average values ranging from 9.7 h to 16.4 h. Meta-analysis, of five studies, showed a pooled mean daily eating window of 11.3 h (95% CI 11.0, 11.7). Large variations in eating windows exist across different study populations; however, the pooled data suggest that it may be possible to design time-limited eating interventions in paediatric populations aimed at reducing eating windows. Further high-quality research, investigating eating windows and subsequent associations with health outcomes, is needed.

Lifestyle Factors Associated With Frequent Recurrent Headaches in Children and Adolescents: A Canadian Population-Based Study

BACKGROUND AND OBJECTIVES

Lifestyle behaviors have been postulated to affect headache frequency in youth and are often the primary target of self-management recommendations. Our study aimed to assess the association between various lifestyle factors and frequent recurrent headaches in children and youth.

METHODS

Children and adolescents aged 5-17 years were enrolled in a large cross-sectional Canadian population-based health survey, completed on January 31, 2019. Headache frequency was dichotomized into "approximately once/week or less" or ">once/week" (defined as frequent recurrent headaches). The association between frequent headaches and meal schedules, screen exposure, physical activity, chronotype, and frequent substance use/exposure (alcohol, cigarettes, electronic cigarettes, and cannabis) was assessed using both unadjusted logistic regression models and models adjusted for age/sex. Fully adjusted models examined the odds of frequent headaches according to all exposures. Survey design effects were accounted for using bootstrap replicate weighting.

RESULTS

There were an estimated nweighted = 4,978,370 eligible participants in the population. The mean age was 10.9 years (95% CI 10.9-11.0); 48.8% were female; 6.1% had frequent headaches. Frequent headaches were associated with older age (odds ratio [OR] = 1.31, 95% CI 1.28-1.34, p < 0.001) and female sex (OR = 2.39, 95% CI 2.08-2.75, p < 0.001). In models adjusted for age/sex, the odds of frequent headaches decreased with meal regularity (adjusted OR [aOR] = 0.90, 95% CI 0.89-0.92, p < 0.001) and increased with later chronotype (aOR = 1.10, 95% CI 1.05-1.15, p < 0.001) and excess screen exposure (≥21 hours vs none in past week: aOR = 2.97, 95% CI 1.53-5.77, p = 0.001); there was no significant association with reported physical activity (aOR = 0.95, 95% CI 0.67-1.34, p = 0.77). In 12- to 17-year-olds, frequent headaches were associated with frequent alcohol use (≥1/wk vs never: aOR = 3.50, 95% CI 2.18-5.62, p < 0.001), binge drinking (≥5 times in past month vs never: aOR = 5.52, 95% CI 2.95-10.32, p < 0.001), smoking cigarettes (daily vs never: aOR = 3.81, 95% CI 1.91-7.62, p < 0.001), using e-cigarettes (daily vs never: aOR = 3.10, 95% CI 2.29-4.20, p < 0.001), and cannabis use (daily vs never: aOR = 3.59, 95% CI 2.0-6.45, p < 0.001). In the entire sample, daily exposure to smoking inside the house was associated with frequent headaches (aOR = 2.00, 95% CI 1.23-3.27, p = 0.005).

DISCUSSION

Several lifestyle behaviors were associated with frequent headaches in children and youth, such as meal irregularity, late chronotype, prolonged screen exposure, and frequent substance use/exposure, suggesting that these are potential modifiable risk factors to target in this population.

Association of the timing of evening eating with BMI Z-score and waist-to-height ratio among preschool-aged children in Finland

Later timing of eating has been associated with higher adiposity among adults and children in several studies, but not all. Moreover, studies in younger children are scarce. Hence, this study investigated the associations of the timing of evening eating with BMI Z-score and waist-to-height ratio (WHtR), and whether these associations were moderated by chronotype among 627 preschoolers (3-6-year-olds) from the cross-sectional DAGIS survey in Finland. Food intake was measured with 3-d food records, and sleep was measured with hip-worn actigraphy. Three variables were formed to describe the timing of evening eating: (1) clock time of the last eating occasion (EO); (2) time between the last EO and sleep onset; and (3) percentage of total daily energy intake (%TDEI) consumed 2 h before sleep onset or later. Chronotype was assessed as a sleep debt-corrected midpoint of sleep on the weekend (actigraphy data). The data were analysed with adjusted linear mixed effects models. After adjusting for several confounders, the last EO occurring closer to sleep onset (estimate = -0·006, 95 % CI (-0·010, -0·001)) and higher %TDEI consumed before sleep onset (estimate = 0·0004, 95 % CI (0·00003, 0·0007)) were associated with higher WHtR. No associations with BMI Z-score were found after adjustments. Clock time of the last EO was not significantly associated with the outcomes, and no interactions with chronotype emerged. The results highlight the importance of studying the timing of eating relative to sleep timing instead of only as clock time.

Mediating roles of sleep quality and resilience in the relationships between chronotypes and mental health symptoms

Sleep and mental health are intrinsically intertwined, but not every individual with problems sleeping develops a mental health disorder. This study examined the association among chronotypes, resilience, sleep quality and mental health symptoms amongst otherwise healthy individuals. Two hundred adults (Mage = 27.75 ± 5.11, 68% female) with no previous diagnosis of mental illness were recruited and filled in a set of questionnaires measuring chronotypes, sleep quality, depression and anxiety symptoms. The findings from the path analysis showed that the morning type had a statistically significant direct effect on a range of sleep quality indices. These included better subjective sleep quality, shortened sleep latency, and fewer daytime dysfunctions, as well as a higher level of resilience. However, it did not significantly affect depression and anxiety symptoms. In addition, the morning type had statistically significant indirect effects on a higher level of resilience and fewer depression and anxiety symptoms through the mediating effect of sleep quality indices. Findings from this study support that morning type is associated with better resilience and psychological health, which is mediated through better sleep quality.

Circadian modulation of the time course of automatic and controlled semantic processing

We investigated whether chronotype and time-of-day modulate the time course of automatic and controlled semantic processing. Participants performed a category semantic priming task at either the optimal or non-optimal time of day. We varied the prime-target onset asynchrony (100-, 450-, 650-, and 850-ms SOAs) and kept the percentage of unrelated targets constant at 80%. Automatic processing was expected with the short SOA, and controlled processing with longer SOAs. Intermediate-types (Experiment 1) verified that our task was sensitive to capturing both types of processes and served as a reference to assess themin extreme chronotypes. Morning-type and evening-type participants (Experiment 2) differed in the influence of time of testing on priming effects. Morning-types applied control in all conditions, and no performance modulation by time-of-day was observed. In contrast, evening-types were most adversely affected by the time of day to shift from automatic-based to controlled-based responses. Also, they were considerably affected in successfully implementing controlled processing with long intervals, particularly at the non-optimal time of day, with inhibitory priming showing only a marginally significant effect at the longest SOA. These results suggest that extreme chronotypes may be associated with different styles of cognitive control. Morning-types would be driven by a proactive control style, whereas a reactive control style might be applied by evening-types.

Circadian rhythmicity in schizophrenia male patients with and without substance use disorder comorbidity

Circadian rhythmicity is associated to clinical variables that play an important role in both schizophrenia (SZ) and substance use disorders (SUD), although the characteristics of the coexistence of these two diagnoses (SZ +) remain mostly unknown. Hence, we studied a sample of 165 male patients divided in three groups each of 55, according to their diagnoses (SZ + , SZ, and SUD), as well as a healthy control (HC; n = 90) group. Alongside with sociodemographic and clinical variables, circadian rhythms were registered through a sleep-wake data structured interview, a circadian typology questionnaire, and distal skin temperature (DST) using the Thermochron iButton every 2 min during 48 h. Analyses showed that SZ + and SZ patients presented a longer sleep (delay in wake-up time) and mostly an intermediate circadian typology, while SUD patients slept less hours, displaying a morning typology. The DST showed the highest daily activation and stability for the SUD group, even when compared with the HC group. The presence of schizophrenia (SZ + and SZ) was related to a DST pattern with a reduced amplitude determined by a wakefulness impairment, which was more pronounced for SZ patients whose sleep period was adequate. The assessment of circadian rhythms in under treatment male patients with SZ should be focused on the diurnal period as a possible marker of either treatment adherence or patient's recovery, irrespective of the presence of a comorbid SUD. Further research with additional objective measures may provide knowledge transferable to therapeutic strategies and could be useful to establish possible endophenotypes in the future.

Effects of a chronotype-adapted diet on weight loss, cardiometabolic health, and gut microbiota: study protocol for a randomized controlled trial

BACKGROUND

Obesity and its associated health complications have become a global public health concern, necessitating innovative approaches to weight management. One emerging area of research focuses on the influence of chronotype, an individual's preferred timing for daily activities, on eating habits, weight regulation, and metabolic health. Recent observational studies suggest that the misalignment between an individual's chronotype and external cues, such as meal timing, may contribute to metabolic dysregulation and obesity, but evidence from intervention studies is still limited. This study protocol describes a randomized controlled trial designed to explore the effects of a chronotype-adapted diet, compared with a diet with a conventional calorie distribution, on weight loss, cardiometabolic health, and gut microbiota composition.

METHODS

A total of 150 overweight/obese adults will be recruited for this 4-month parallel-group, randomized, two-arm, open-label, superiority trial with 1:1 allocation ratio. Participants will be randomly assigned to either the intervention group or the control group. The intervention group will receive a low-calorie chronotype-adapted diet with a calorie distribution adapted to the individual chronotype (morning or evening), optimizing meal timing according to their peak metabolic periods. The control group will follow a standardized low-calorie healthy eating plan without considering chronotype. Both diets will have equivalent daily calorie content, adjusted according to gender and starting weight. Anthropometric measurements, body composition, blood, and fecal samples will be obtained from each participant at the beginning and the end of the study. The primary outcome is weight change from baseline. Secondary outcomes are changes from baseline in body mass index (BMI), fat mass, lipid and glycemic profile, fecal microbiota profile, and short-chain fatty acids (SCFAs).

DISCUSSION

The results of this randomized controlled trial have the potential to advance our understanding of the complex interactions between chronotype, diet, body weight, and health outcomes. By providing evidence for personalized dietary interventions based on individuals' circadian preferences, this research could offer insights into personalized nutrition strategies. Such knowledge could guide the development of innovative dietary interventions to optimize the prevention and management of overweight and obesity, while also improving the risk profile of these individuals.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05941871. Registered on 18 May 2023.

Personality Risk Factors for Vape Use amongst Young Adults and Its Consequences for Sleep and Mental Health

(1) Background: The surge in vape (e-cigarette) use among young adults is concerning, as there is limited knowledge about risk factors and health consequences. This study explores the personality traits linked to vape use, and associations between vaping and chronotype, sleep quality, and mental health, among young adults. (2) Methods: 316 participants, aged 18-25, completed measurements of mindfulness, rumination, self-compassion, anxiety/depression, chronotype, and sleep quality. (3) Results: the vape user group scored significantly lower on mindfulness, higher on rumination, and lower on self-compassion. Vape users were more likely to be evening types and had significantly lower sleep quality and higher anxiety symptoms, as well as higher alcohol use and loneliness (at trend) (4) Conclusions: These novel findings enhance our understanding of what might predispose young adults to vaping and the potential impact on their mental health and sleep quality. Findings point to specific cognitive/personality traits as vaping risk factors, which could inform intervention strategies.

The associations between different types of infections and circadian preference and shift work

Disturbed sleep and circadian disruption are reported to increase the risk of infections. People with an evening circadian preference and night workers typically report insufficient sleep, and the aims of the present study were to investigate possible associations between various types of infections and circadian preference and shift work status. Data were collected from an online cross-sectional survey of 1023 participants recruited from the Norwegian practice-based research network in general practice - PraksisNett. The participants completed questions about circadian preference (morning type, intermediate type, evening type), work schedule (day work, shift work without nights, shift work with night shifts), and whether they had experienced infections during the last three months (common cold, throat infection, ear infection, sinusitis, pneumonia/bronchitis, COVID-19, influenza-like illness, skin infection, gastrointestinal infection, urinary infection, venereal disease, eye infection). Data were analyzed with chi-square tests and logistic regression analyses with adjustment for relevant confounders (gender, age, marital status, country of birth, children living at home, and educational level). Results showed that evening types more often reported venereal disease compared to morning types (OR = 4.01, confidence interval (CI) = 1.08-14.84). None of the other infections were significantly associated with circadian preference. Shift work including nights was associated with higher odds of influenza-like illness (OR = 1.97, CI = 1.10-3.55), but none of the other infections. In conclusion, neither circadian preference nor shift work seemed to be strongly associated with risk of infections, except for venereal disease (more common in evening types) and influenza-like illness (more common in night workers). Longitudinal studies are needed for causal inferences.

Testing the modulation of self-related automatic and others-related controlled processing by chronotype and time-of-day

We assessed whether self-related automatic and others-related controlled processes are modulated by chronotype and time-of-day. Here, a shape-label matching task composed of three geometrical shapes arbitrarily associated with you, friend, and stranger was used. Twenty Morning-types, and twenty Evening-types performed the task at the optimal and non-optimal times of day (i.e., 8 AM, or 8:30 PM). Morning-types did not exhibit noticeable synchrony effects, thus proving the better adaptation of these participants to non-optimal moments of the day as compared to Evening-types. Contrary to our predictions regarding the absence of automatic-processing modulation and the presence of controlled-processing influences by time-of-day, we found an influence on self-related but not others-related processing only in Evening-type participants. Although brain structures are not directly tackled, we argue that such modulation may be due to the dependence of the activation of the ventromedial prefrontal cortex (VMPFC), an essential component of the self-attention network on circadian rhythms.

The relationship between multiple sleep dimensions and obesity in adolescents: A systematic review

Sleep is an involuntary behaviour, biologically fundamental to survival and wellbeing. However, sleep is increasingly neglected, with significant health implications. Recent research has identified associations between sleep duration, quality, timing and risk of overweight/obesity in children and adults. The aim of this review was to systematically identify and examine research that investigates the relationships between multiple objective and subjective sleep outcomes and objective adiposity measures in adolescents. A systematic review of literature, published to December 2022, was conducted using ten bibliographic databases. Search terms included objective and subjective sleep/circadian rhythm outcomes, objective adiposity measurements, and adolescents aged 8-18 years. Eighty-nine studies were included in the final review. Sleep outcomes were synthesized into three sleep domains: pre-sleep, during sleep and post-sleep outcomes. In summary, pre-sleep outcomes (including poor sleep hygiene, later chronotype and increased variability and later sleep timings) and increased sleep disturbance are consistently significantly associated with increased obesity and adiposity in adolescents. The relationship between during-sleep outcomes (sleep quality and efficiency) with adiposity and obesity measures was mixed. These findings suggest that adapting an individual's schedule to best suit chronotype preference and improving sleep hygiene, including a consistent bedtime routine, could reduce adiposity and obesity in adolescents.

Associations of social jetlag with physical activity and sedentary behaviour in children and adolescents: A systematic review and meta-analysis

Sleep and daytime movement behaviours occur co-dependently with each other within a finite 24 h day. Sleep parameters other than sleep duration, such as social jetlag and chronotype, have been linked to health problems and unhealthy behaviours among children and adolescents. Given the increasing number of studies examining sleep timing/chronotype and weight-related behaviours, including physical activity and sedentary behaviour, in the past decade, this systematic review and meta-analysis collated and evaluated the evidence on the relationships of social jetlag and chronotype with physical activity and sedentary behaviour among children and adolescents aged 3-17 years. Seven databases were searched on 16 March 2022, and 52 studies were identified as eligible for inclusion, 47 of which were suitable for the meta-analysis. A positive association was found between social jetlag and screen media use (r = 0.14, 95% CI: 0.04-0.24; I2  = 96%; p = 0.008). The morning chronotype was associated with a higher level of physical activity and a lower level of sedentary behaviour than the evening chronotype. No relationship was found between social jetlag and physical activity. The magnitude of heterogeneity among the included studies was high. Further experimental studies are urgently required to understand how circadian preference or misalignment affects activity behaviours. Interventions to promote an active lifestyle in young populations should consider their circadian preference, especially among individuals with the evening chronotype.

Beat the Clock: Assessment of Night Eating Syndrome and Circadian Rhythm in a Sample of Greek Adults

The night eating syndrome (NES) is characterized by excessive food intake during the evening and night hours, with 25% of the daily intake being consumed post-dinner, paired with ep-isodes of nocturnal food intake, at a frequency of more than twice weekly. The NES has been associated with a misaligned circadian rhythm related to a delay in overall food intake, increased energy and fat consumption. The present cross-sectional study aimed to assess NES in a Greek population and evaluate possible links between NES and chronotype. NES was assessed using the Night Eating Questionnaire (NEQ), and circadian rhythm, sleep and mood were evaluated with the Sleep, Circadian Rhythms, and Mood (SCRAM) questionnaire. A total of 533 adults participated in the study. A relatively high prevalence of NES was revealed, with more than 8.1% (NEQ ≥ 30) of the participants reporting experiencing NES symptoms, depending on the NEQ threshold used. Most participants had the intermediate chronotype. NEQ score was positively associated with the morning chronotype, and SCRAM was negatively related to "Good Sleep". Each point increment in the depression score was associated with 6% higher odds of NES. The early identification of NES gains importance in clinical practice, in a collective effort aiming to reduce NES symptomatology and its detrimental health effects.

The influence of childhood trauma and chronotype on suicide attempts in Chinese emerging adults with severe depressive symptoms

BACKGROUND

Studies have investigated how adults with severe depressive symptoms are more likely to attempt suicide, and these adults often have traumatic experiences and chaotic sleep/wake rhythms. Thus, this study using Latent class analysis aimed to investigate the relationship between childhood trauma class, chronotype, and suicide attempts among emerging adults with severe depressive symptoms.

METHODS

This study was conducted among emerging adults with severe depressive symptoms covering 63 Universities in Jilin Province, China. A total of 1,225 emerging adults (mean age = 19.6 ± 1.78) constructed the final sample. In addition to measuring socio-demographic characteristics, the Childhood Trauma Questionnaire-Short Form, the Single-Item Chronotyping, and a single item for suicide attempts were used to evaluate childhood trauma, chronotype, and suicide attempts, respectively. Latent class analysis was applied to identify the classes of childhood trauma within emerging adults who had severe depressive symptoms. Hierarchical logistic regression models were run to investigate the effects of socio-demographic characteristics, chronotype, and childhood trauma class on suicide attempts.

RESULTS

Three latent classes were identified: the Low-risk for childhood trauma class, the Neglect class, and the High-risk for childhood abuse class. Those who suffered sexual, emotional, and physical abuse at the same time were divided into the High-risk for childhood abuse class, and were significantly more likely to experience suicide attempts than those in the Neglect class (OR = 1.97, 95%CI = 1.34-2.89, p < 0.001) and the Low-risk for childhood trauma class (OR = 2.28, 95% CI = 1.50-3.46, p < 0.001). In terms of chronotype, the results showed that the chaotic type was a risk factor for suicide attempts when compared with the evening type (OR = 0.46, 95%CI = 0.27-0.78, p < 0.01), the moderately active type (OR = 0.53, 95%CI = 0.31-0.89, p < 0.05), and the daytime type (OR = 0.42, 95%CI = 0.21-0.86, p < 0.05). Overall, the significant risk factors for suicide attempts included being female, living in an urban area, having experienced sexual, emotional, and physical abuse simultaneously, and having a chaotic chronotype.

CONCLUSION

Emerging adults suffering sexual, emotional, and physical abuse at the same time and identifying with chaotic chronotype showed a higher risk of attempting suicide. The findings provided a clinical reference to quickly identify those at high risk of suicide attempts among emerging adults with severe depressive symptoms.

A more accurate assessment of circadian typology is achieved by asking persons to indicate their preferred times rather than comparing themselves with most people

The aim of the present work was to compare two circadian questionnaires: the Preference Scale (PS) and the reduced version of the Morningness-Eveningness Questionnaire (rMEQ). A sample of 849 (35.10% men) university students, 421 of whom were Spanish (27.55% men; mean age 21.07 + 2.31) and 428 Italian (42.52% men; mean age 23.26 + 3.01), were administered both questionnaires. Gender (higher morningness in women) and nationality (higher eveningness in Spaniards) differences were replicated with rMEQ but not with PS, in which an inverse association between nationality and circadian preference was observed (i.e. higher morningness in Spaniards). Taking into account that the formulation of the rMEQ items, with its specific times, makes the answers less influenced by socio-cultural bias, we conclude that rMEQ is preferable to PS when evaluating circadian preference in young adults.

Pressure Building Against the Clock: The Impact of Circadian Misalignment on Blood Pressure

PURPOSE OF REVIEW

Misalignment between the endogenous biological timing system and behavioral activities (i.e., sleep/wake, eating, activity) contributes to adverse cardiovascular health. In this review, we discuss the effects of recurring circadian misalignment on blood pressure regulation and the implications for hypertension development. Additionally, we highlight emerging therapeutic approaches designed to mitigate the negative cardiovascular consequences elicited by circadian disruption.

RECENT FINDINGS

Circadian misalignment elicited by work schedules that require individuals to be awake during the biological night (i.e., shift work) alters 24-h blood pressure rhythms. Mechanistically, circadian misalignment appears to alter blood pressure via changes in autonomic nervous system balance, variations to sodium retention, dysregulation of endothelial vasodilatory responsiveness, and activation of proinflammatory mechanisms. Recurring circadian misalignment produced by a mismatch in sleep timing on free days vs. work days (i.e., social jetlag) appears to have no direct effects on prevailing blood pressure levels in healthy adults; though, circadian disruptions resulting from social jetlag may increase the risk of hypertension through enhanced sympathetic activation and/or obesity. Furthermore, social jetlag assessment may be a useful metric in shift work populations where the magnitude of circadian misalignment may be greater than in the general population. Circadian misalignment promotes unfavorable changes to 24-h blood pressure rhythms, most notably in shift working populations. While light therapy, melatonin supplementation, and the timing of drug administration may improve cardiovascular outcomes, interventions designed to target the effects of circadian misalignment on blood pressure regulation are warranted.

The effect of time of day on Special Judo Fitness Test in active judokas: Evaluation in terms of chronotype

The present cross-sectional study aims to examine the effect of time of day on the judo-specific performance in judokas, considering their chronotypes. Twenty-four male judokas participated in the study where the Morningness-Eveningness Questionnaire was administered, and on it, they were divided into morning-type (MT:12-judokas) and evening-type groups (ET:12-judokas). Afterwards, the Special Judo Fitness Test (SJFT) was applied to both groups at three different times (morning: 09:00 h, afternoon: 13:00 h and evening: 17:00 h) with body temperature measured before and after every SJFT performance. As a result, the Group*Test Time interaction significantly affected overall throwing performance during SJFT [F(2,44) = 29.437, p = 0.001, η2p: .572]. Furthermore, a significant time effect was found for the SJFT index [F(2,44) = 5.118, p = 0.010, η2p: .189] and for the Group*Test Time interaction with the mean value of the index [F(2,44) = 24.424, p < 0.001, η2p: .526]. Furthermore, body temperature had a significant time effect [F(2,44) = 301.454, p < 0.001, η2p: .932] and the Group*Test Time interaction [F(2,44) = 5.802, p = 0.006, η2p: .209]. In conclusion, coaches and exercise experts should consider judo athletes' chronotype when planning special training programs to improve judo-specific anaerobic capacity. Furthermore, to minimize the impact of time of day and chronotype on athletes' performance in competitions, it is recommended that MT athletes develop their judo-specific anaerobic capacity in the evening hours, when their performance is lower, while ET athletes should do so in the morning hours when their performance is lower via randori training.

Taking biological rhythms into account: From study design to results reporting

Numerous physiological and behavioral processes in living organisms exhibit strong rhythmicity and are regulated within a 24-hour cycle. These include locomotor activity and sleep patterns, feeding-fasting cycles, hormone synthesis, body temperature, and even mood and cognitive abilities, all of which are segregated into different phases throughout the day. These processes are governed by the internal timing system, a hierarchical multi-oscillator structure conserved across all organisms, from bacteria to humans. Circadian rhythms have been seen across multiple taxonomic kingdoms. In mammals, a hierarchical internal timing system is comprised of so-called central and periphereal clocks. Although these rhythms are intrinsic, they are under environmental influences, such as seasonal temperature changes, photoperiod variations, and day-night cycles. Recognizing the existence of biological rhythms and their primary external influences is crucial when designing and reporting experiments. Neglecting these physiological variations may result in inconsistent findings and misinterpretations. Thus, here we propose to incorporate biological rhythms into all stages of human and animal research, including experiment design, analysis, and reporting of findings. We also provide a flowchart to support decision-making during the design process, considering biological rhythmicity, along with a checklist outlining key factors that should be considered and documented throughout the study. This comprehensive approach not only benefits the field of chronobiology but also holds value for various other research disciplines. The insights gained from this study have the potential to enhance the validity, reproducibility, and overall quality of scientific investigations, providing valuable guidance for planning, developing, and communicating scientific studies.

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.

Association between chronotype and metabolic-associated fatty liver disease in employed adults: A longitudinal study in Southwestern China

The circadian system is an essential physiological regulator of mammals, and sleep chronotype may be associated with the risk of metabolic disorders. However, evidence regarding the role of sleep chronotype in the development of metabolic-associated fatty liver disease (MAFLD) is scarce, particularly in employed adults. We conducted a longitudinal study of 1,309 employed adults in Southwestern China with a five-year follow-up from 2017 to 2021. MAFLD was assessed by the presence of hepatic steatosis using abdominal ultrasonography, overweight/obese status, diabetes mellitus, metabolic dysregulation, or elevation of high-sensitivity C-reactive protein. Chronotype was assessed by the Morning and Evening Questionnaire-5 (MEQ-5). The logistic random effects model was applied to analyze the 5-year panel data to estimate the association between chronotype and MAFLD, and the potential effect modification of demographics on such association. The MAFLD prevalence of participants was 38.6% at baseline and showed an increasing trend during follow-up (p for trends < 0.05). Compared with morning chronotype, evening chronotype was positively associated with MAFLD (OR = 2.19, 95%CI: [1.09, 4.40]) after controlled for covariates. Age, sex, ethnicity, and educational level did not modify the association between chronotype and MAFLD. These findings suggest that improving circadian rhythms could reduce the risk of MAFLD and chronic disease burden among employed adults.

Is chronotype linked with adherence to the Mediterranean diet among adolescents? The EHDLA study

BACKGROUND

No previous study has evaluated the relationship between chronotype and adherence to the Mediterranean diet among adolescents. The aim of the present study was to assess the association between chronotype and adherence to the Mediterranean diet in a sample of Spanish adolescents aged 12-17 years.

METHODS

This study examined secondary data from 820 adolescents (55.5% girls) from the Eating Healthy and Daily Life Activities (EHDLA) study, which included a representative sample of adolescents aged 12-17 years from the Valle de Ricote (Region of Murcia, Spain). Adolescents' chronotype was evaluated with the Morningness/Eveningness Scale in Children. Adherence to the Mediterranean diet was determined through the Mediterranean Diet Quality Index for Children and Teenagers.

RESULTS

The proportion of adolescents with an optimal Mediterranean diet was 37.6%. In relation to chronotype, we found that 24.5%, 69.4%, and 6.1% of the adolescents were classified as morning, intermediate, and evening types, respectively. After adjusting for several covariates, both evening- and intermediate-type adolescents showed lower odds of having optimal adherence to the Mediterranean diet (evening-type: odds ratio [OR] = 0.30, confidence interval [CI] 95% 0.12-0.72; intermediate-type: OR = 0.62, CI 95% 0.44-0.87) than morning-type adolescents.

CONCLUSIONS

Chronotype could affect adherence to the Mediterranean Diet in adolescents, so it should be a factor to be considered in future studies assessing eating habits.

IMPACT

No previous study has evaluated the relationship between chronotype and adherence to the Mediterranean diet among adolescents. Both evening- and intermediate-type adolescents showed lower odds of having optimal Mediterranean diet adherence than morning-type adolescents. These findings may indicate a need to promote eating healthy habits based on a more holistic approach, not only on the total energy expenditure or in specific food groups but also on the chronotype.

Chronotype is differentially associated with lifetime mood and panic-agoraphobic spectrum symptoms in patients with bipolar disorder and healthy controls

OBJECTIVE

Although the association between chronotype and mood disorders has been consistently reported, conversely, attempts to measure the association between chronotype and anxiety symptoms have generated inconsistent results. We aimed at evaluating whether chronotype (assessed through subjective and objective measures) is associated with lifetime mood and panic-agoraphobic spectrum symptoms in healthy controls (HCs) and in patients with bipolar disorder (BD).

METHODS

Overall, 173 subjects, patients with BD in euthymic phase (n = 76) and HC (n = 97), were evaluated through the reduced Morningness-Eveningness Questionnaire (rMEQ), actigraphy monitoring and mood and panic-agoraphobic spectrum self-report (MOODS-SR and PAS-SR). The discrepancy between objective (actigraphic-based) versus subjective (rMEQ-based) circadian typology was estimated through the Circadian Classification Discrepancy Index (CCDI).

RESULTS

rMEQ-based evening chronotype (ET) was associated with higher scores in MOODS-SR depressive and rhythmicity and vegetative functions domains in HC and BD.Both ET and morning chronotypes (MT) were associated with higher PAS-SR scores in BD only. Actigraphic-based MT was associated with higher MOODS-SR depressive scores in HC. Likewise, the discrepancy between actigraphic-based and rMEQ-based circadian typology was associated with depressive symptoms in HC only.

CONCLUSION

Self-reported ET was consistently associated with mood symptoms, while associations with panic-agoraphobic symptoms only emerged in BD and involved both extreme chronotypes. The discrepancy between the preferred circadian typology (rMEQ-based) and the actual one (actigraphic-based) could contribute to depressive symptoms in HC. These results pave the way for interventional studies targeting circadian typology in an attempt to prevent or treat mental health disorders.

The thief of (bed)time: Examination of the daily associations between bedtime procrastination and multidimensional sleep health

OBJECTIVES

Sleep insufficiency is associated with increased risk of morbidity and mortality. Bedtime procrastination, or the needless and voluntary delay in sleep, is a sleep-related behavior which may interfere with sleep health. The objective of this study is to comprehensively examine the daily associations among bedtime procrastination and measures of sleep regularity, satisfaction, timing, efficiency, and duration.

METHODS

Two hundred and eighty young adult participants (79% female; Mage=24.4) completed daily sleep diaries and measures of bedtime procrastination and sleep restoration over 14days, in addition to measures of chronotype. Multilevel models were constructed to examine the associations between bedtime procrastination and sleep health.

RESULTS

Greater bedtime procrastination was associated with poorer sleep health, including poorer self-reported sleep restoration, later sleep timing, less efficient sleep, and shorter sleep duration. These associations were significant at both within- and between-person levels, and persisted after statistically adjusting for individuals' chronotypes.

CONCLUSIONS

This study offers bedtime procrastination as a putative mechanism for poor sleep health and finds that the associated risk of poor sleep from bedtime procrastination is independent of chronotype. Results presented here suggest that bedtime procrastination may be a relevant behavior in the development or maintenance of sleep and sleep-related disorders.

Mediation analysis of chronotype, sleep-related factors, and depressive symptoms among workers: a cross-sectional study

Background

This study aimed to examine the impact of chronotype on depressive symptoms and explore the mediating effects of sleep quality, pre-sleep cognitive arousal, and social jetlag in a sample of wage earners.

Methods

A total of 3,917 waged workers were surveyed online in July 2022. Logistic regression and mediation analysis were used to assess the relationship between chronotype (morningness, intermediate, and eveningness) and depressive symptoms (Patient Health Questionnaire ≥ 5), and the mediating effects of Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), and Pre-Sleep Arousal Scale (PSAS). All analyses were adjusted for age, education level, income level, marital status, coffee consumption, alcohol consumption, physical activity, occupation, employment status, and working hours to calculate odds ratios (ORs).

Results

The chronotypes of all the participants were divided into morningness (4.7%), intermediate (93.5%), and eveningness (1.8%). Multiple logistic regression analysis showed an increased risk of depression in the eveningness chronotype (OR: 2.96; 95% confidence interval [CI]: 1.51, 5.86). Regarding the mediation analysis, ISI mediated 28.44% (95% CI: 16.39-40.5), PSQI for 31.25% (95% CI: 19.36, 43.15), and PSAS-Cognitive Score (PSAS-C) for 23.58% (95% CI: 10.66, 36.50) of the association between chronotype and depressive symptoms. However, social jetlag did not significantly mediate this relationship. (percentage mediated = 0.75%, 95% CI: -3.88, 5.39).

Conclusions

Evening chronotypes exhibit an increased risk of depressive symptoms, which ISI, PSQI, and PSAS-C partially mediated. This suggests that interventions to improve sleep quality and maintain adequate sleep habits may effectively prevent and treat depression in employees with an eveningness chronotype.

Effects of chronotype-tailored bright light intervention on post-treatment symptoms and quality of life in breast cancer survivors

PURPOSE

Bright light therapy holds promise for reducing common symptoms, e.g., fatigue, experienced by individuals with cancer. This study aimed to examine the effects of a chronotype-tailored bright light intervention on sleep disturbance, fatigue, depressive mood, cognitive dysfunction, and quality of life among post-treatment breast cancer survivors.

METHODS

In this two-group randomized controlled trial (NCT03304587), participants were randomized to receive 30-min daily bright blue-green light (12,000 lx) or dim red light (5 lx) either between 19:00 and 20:00 h or within 30 min of waking in the morning. Self-reported outcomes and in-lab overnight polysomnography sleep study were assessed before (pre-test) and after the 14-day light intervention (post-test).

RESULTS

The sample included 30 women 1-3 years post-completion of chemotherapy and/or radiation for stage I to III breast cancer (mean age = 52.5 ± 8.4 years). There were no significant between-group differences in any of the symptoms or quality of life (all p > 0.05). However, within each group, self-reported sleep disturbance, fatigue, depressive mood, cognitive dysfunction, and quality of life-related functioning showed significant improvements over time (all p < 0.05); the extent of improvement for fatigue and depressive mood was clinically relevant. Polysomnography sleep findings showed that a number of awakenings significantly decreased (p = 0.011) among participants who received bright light, while stage 2 sleep significantly increased (p = 0.015) among participants who received dim-red light.

CONCLUSION

The findings support using light therapy to manage post-treatment symptoms in breast cancer survivors. The unexpected symptom improvements among dim-red light controls remain unexplained and require further investigation.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03304587, October 19, 2017.

Why do owls have it worse? Mediating role of self-perceptions in the links between diurnal preference and features of mental health

Recent research provides evidence for the negative social perceptions of evening chronotypes and their consequences on mental health. However, there is a lack of studies indicating whether these negative, socially shared beliefs may become internalized in negative self-perceptions of evening-types (E-types). The present article provides a seminal empirical analysis of the role of self-liking and self-competence in the associations between chronotype and both depressiveness and well-being. In the first part of the study, the participants completed the Composite Scale of Morningness. On the basis of the chronotype cut-off criteria for Composite Scale of Morningness distribution, 100 individuals were classified as morning-types (M-types) and 66 individuals as E-types. Therefore, 166 participants (80 women and 86 men) aged 18-36 years (M ± SD: 29.27 ± 4.81 years) took part in the second part of the study, and completed questionnaires measuring self-liking, self-competence, life satisfaction, positive and negative affect, and depressiveness. Results show that E-types scored lower in self-liking, self-competence and subjective well-being, and higher in depressive symptoms than M-types. Controlling for age and gender, we obtained significant mediation effects, showing that the relationship between chronotype and subjective well-being might stem from the lower levels of self-liking and self-competence among E-types, and that the relationship between chronotype and depressive symptoms might stem from the lower level of self-liking among E-types. Our results suggest that self-liking and self-competence are important antecedents of lower well-being and higher depressiveness reported by E-types. Socially shared stereotypes of M-types and E-types can be internalized by the extreme chronotypes, which may significantly affect their psychological health.

Blame it on the "night owls": Perceived discrimination partly mediates the effects of morningness-eveningness on positive and negative affect

The well-established effects of evening preference on diminished well-being and poorer mental health are usually explained in terms of common genetic bases of eveningness and negative emotionality and/or the discrepancy between biological and social clocks, experienced far more frequently by the Evening-types. However, recent studies provide evidence for the negative stereotyping of evening chronotypes which may lead to unexpectedly pronounced social stigma and its consequences. The present article provides a seminal empirical analysis of the role of perceived chronotype-related discrimination in the association between morningness-eveningness and both positive affect and negative affect. The study was conducted on a gender-balanced sample of 768 individuals aged between 18 and 56 years who filled measures of morningness-eveningness, positive and negative affect, as well as a modified version of the Perceived Devaluation Discrimination scale, tentatively labeled Perceived Chronotype-Related Discrimination scale (https://osf.io/urs8x/), developed to measure the sense of chronotype-based discrimination. Conducted analyses provided evidence for a positive association between eveningness and perceived discrimination. Moreover, perceived discrimination partly mediated the associations between morningness-eveningness and both positive affect and negative affect, explaining 18% and 29% of these effects, respectively. Hence, our results provide initial evidence for yet another mechanism through which chronotype may impact emotional functioning, namely the experience of chronotype-based stigmatisation.