Circadian typology: a comprehensive review

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.

Salivary cortisol concentration and perceived stress measure in response to acute natural stress: The role of morningness-eveningness preference

Chronotype reflects the morningness-eveningness preference over a 24-h period. Significant data indicates meaningful differences between evening types (ET) and morning types (MT) in behavior, personality traits, health and well-being. The aim of this study was to investigate cortisol response and subjective perceived stress of MT and ET individuals in response to an acute natural stressor. Twenty six definite MT (mean age 23.4 ± 1.7) and twenty six definite ET (mean age 23.8 ± 1.3) college students were recruited for this study. Participants were instructed to evaluate their perceived subjective stress and to provide saliva samples for cortisol levels at four different time points: Morning of regular school day, morning immediately before a final exam, afternoon of a regular school day and afternoon immediately before a final exam. For general mood assessment, the participants were also asked to fill out the Positive and Negative Affect Schedule (PANAS) questionnaire. The most outstanding finding of this study was the blunting of cortisol increase in response to acute stress in the morning in the ET group: Salivary cortisol was higher before a final exam only in MT but not in ET. However, no differences between the groups were found in the subjective stress measure. In the PANAS scale, ET showed lower positive affect, and a trend towards a higher negative affect. Overall, our results suggest dysregulation of cortisol response in ET individuals, possibly due to their daily struggle to function in a morning-oriented society. These results further highlight the challenges faced by ET individuals and raise the question of possible interventions to assist them.

Chrononutrition behaviors, sugar-sweetened beverage consumption, sleep quality and the association with body mass index among Malaysian women

The present study aimed to determine the association between chrononutrition behaviors, sugar-sweetened beverage intake, and sleep quality among Malaysian women. A cross-sectional study using a validated, self-administered Chrononutrition Profile Questionnaire, Beverage Questionnaire and Sleep Quality Index were conducted among 934 Malaysian women. Multinomial logistic regression was performed to obtain odds ratios of being overweight/underweight and to test the association with poor sleep quality. 40% of Malaysian women were either overweight or obese and 65.4% had poor sleep quality. We found that breakfast skipping (OR: 4.101; CI: 2.378-7.070), poor evening eating (OR: 4.073; CI: 1.631-10.186), and eating the largest meal at night (OR: 6.970; CI: 1.944-24.994) increased the odds of being underweight. On the other hand, the daily consumption of 100% fruit juices (OR: 1.668; CI: 1.058-1.731), daily consumption of sweetened coffee or tea (OR: 1.707; CI: 1.162-2.508) and consumption of diet soft drinks by 6 times or fewer (OR: 1.484; CI: 1.066-2.064) are associated with increased odds of being overweight. However, when adjusted, only poor evening latency (AOR: 16.638; CI: 1.986-139.383) revealed an increased odd of being underweight. The highest odds predicting poor sleep quality were found for eating the largest meal during dinner (OR: 3.696; CI: 1.967-6.945) and (AOR: 2.194; CI: 1.119-4.304) when adjusted. Hence, the result indicates that multifactorial impacts on women's body weight and recommendations to adjust chrononutrition and sugar-sweetened beverages intake in lifestyle must be done carefully considering other parameters together.

The association between different sleep health dimensions and sex, age, education, circadian preference, and chronic insomnia: a representative population-based study

Objectives

The aims were to explore multidimensional sleep health and the different dimensions of sleep health in the adult Norwegian population in relation to sex, age, education, circadian preference, and chronic insomnia.

Methods

A representative sample of 1028 Norwegians, aged 18 + years completed a cross-sectional web-based survey. Sleep health was measured with the multidimensional RU_SATED scale, which assesses the dimensions of regularity, satisfaction, alertness, timing, efficiency, and duration. Insomnia was assessed with the Bergen Insomnia Scale. Data were analyzed with chi-square tests, t-tests, one-way ANOVAs, and regression analyses, as appropriate. Response rate was 33.5%.

Results

Sleep health was better in males, with increasing age, and with higher educational level, and was poorer in participants with evening preference and chronic insomnia, compared to their respective counterparts. When investigating the different sleep health dimensions, males scored better than females on satisfaction (adjusted odds ratio [aOR] = 0.69, 95% CI = 0.51 to 0.93), timing (aOR = 0.66, 95% CI = 0.49 to 0.88), and efficiency (aOR = 0.68, 95% CI = 0.52 to 0.89). Older age was associated with better scores on regularity and satisfaction, whereas young age was associated with better scores on alertness and duration. High educational level was associated with better scores on alertness, timing, and duration. Evening types scored worse than morning types on regularity (aOR = 0.27, 95% CI = 0.18 to 0.41), satisfaction (aOR = 0.37, 95% CI = 0.26 to 0.53), and timing (aOR = 0.36, 95% CI = 0.26 to 0.51). Participants with chronic insomnia scored worse than participants without insomnia on all six sleep health dimensions.

Conclusions

Sleep health differed significantly in relation to sex, age, education, circadian preference, and chronic insomnia. However, specific group differences were not equally evident in all sleep health dimensions.

The Interactive Role of Sleep and Circadian Rhythms in Episodic Memory in Older Adults

Adequate sleep is essential for healthy physical, emotional, and cognitive functioning, including memory. However, sleep ability worsens with increasing age. Older adults on average have shorter sleep durations and more disrupted sleep compared with younger adults. Age-related sleep changes are thought to contribute to age-related deficits in episodic memory. Nonetheless, the nature of the relationship between sleep and episodic memory deficits in older adults is still unclear. Further complicating this relationship are age-related changes in circadian rhythms such as the shift in chronotype toward morningness and decreased circadian stability, which may influence memory abilities as well. Most sleep and cognitive aging studies do not account for circadian factors, making it unclear whether age-related and sleep-related episodic memory deficits are partly driven by interactions with circadian rhythms. This review will focus on age-related changes in sleep and circadian rhythms and evidence that these factors interact to affect episodic memory, specifically encoding and retrieval. Open questions, methodological considerations, and clinical implications for diagnosis and monitoring of age-related memory impairments are discussed.

Mendelian randomization and colocalization analyses reveal an association between short sleep duration or morning chronotype and altered leukocyte telomere length

Observational studies suggest certain sleep traits are associated with telomere length, but the causal nature of these associations is unclear. The study aimed to determine the causal associations between 11 sleep-related traits and leukocyte telomere length (LTL) through two-sample Mendelian randomization and colocalization analyses using the summary statistics from large-scale genome-wide association studies. Univariable Mendelian randomization indicates that genetically determined short sleep is associated with decreased LTL, while morning chronotype is associated with increased LTL. Multivariable Mendelian randomization further supports the findings and colocalization analysis identifies shared common genetic variants for these two associations. No genetic evidence is observed for associations between other sleep-related traits and LTL. Sensitivity MR methods, reverse MR and re-running MR after removing potential pleiotropic genetic variants enhance the robustness of the results. These findings indicate that prioritizing morning chronotype and avoiding short sleep is beneficial for attenuating telomere attrition. Consequently, addressing sleep duration and chronotype could serve as practical intervention strategies.

The prevalence of temporomandibular disorder and temporomandibular morphology among diverse chronotype profiles

This study investigates the influence of chronotype on the prevalence of temporomandibular joint disorders (TMD) and the morphology of temporomandibular joint (TMJ). According to the Morningness-Eveningness Questionnaire-Self-Assessment, the participants were divided into morning group (n = 30), intermediate group (n = 83), and evening group (n = 30). Thirty participants were randomly selected from the intermediate group for subsequent examination and measurements. The morphology of TMJs was investigated using questionnaire and clinical examination form in Diagnostic Criteria for Temporomandibular Disorder. Meanwhile, the morphological results of TMJs were measured from cone-beam computed tomography images. The prevalence rate of TMD in the morning group (23%) was significantly lower than that in the intermediate group (56.7%), while there was no difference between the evening (53.4%) and intermediate groups. As to morphological measurements, there was no significant difference among three groups in mediolateral width of condylar process, anteroposterior width of condylar process, radius of condyle, medial joint space, lateral joint space, condylar stress angle, horizontal condylar inclination, width of glenoid fossa, depth of glenoid fossa, and posterior joint space, while there was a significant difference in horizontal condylar angle (p = 0.00490), articular eminence inclination (p < .0001), anterior joint space (p = 0.0163), and superior joint space (p = 0.0004). The morphology of TMJ in the morning group was better than that in the evening and intermediate groups. An association was found between TMD prevalence, temporomandibular morphology, and chronotype.

Chronotype is associated with addiction-like eating behavior, mindful eating and ultra-processed food intake among undergraduate students

This study aimed to investigate the relationships between chronotype and addiction-like eating behavior, mindful eating and ultra-processed food consumption among undergraduate students. Specific and validated scales were used in order to evaluate chronotype, addiction-like eating behavior and mindful eating (N = 605). Dietary intake was determined by food frequency questionnaire and percentage energy from ultra-processed food was calculated. Self-reported weights and heights were obtained from the participants. Mean scores of scales, social jetlag, energy intake, ultra-processed food intake and BMI were compared by chronotypes. Associations between chronotype, addiction-like eating behavior, mindful eating, ultra-processed food consumption and BMI were determined by Pearson's test. The relationships between chronotype and addiction-like eating behavior, mindful eating and ultra-processed food intake were assessed by linear regression models and adjusted for sex, BMI, energy intake, season, smoking and alcohol consumption. Evening-type participants had higher scores of social jetlag (2.01 ± 0.09), appetitive drive (26.02 ± 0.63), low dietary control (20.50 ± 0.41), addiction-like eating behavior (46.52 ± 0.85), lower scores of recognition (21.91 ± 0.43) and higher percentage energy from ultra-processed food (32.24 ± 1.26%). Chronotype score showed negative associations with addiction like eating behavior (β=-0.247, p < 0.001) and ultra-processed food consumption (β=-0.247, p < 0.001), and a positive association with recognition (β = 0.124, p < 0.001). Results suggest that chronotype is inversely associated with addiction-like eating behavior and ultra-processed food consumption, and positively associated with mindful eating among undergraduate students.

Hypnagogic states are quite common: Self-reported prevalence, modalities, and gender differences

The hypnagogic state refers to the transitional phase between wakefulness and sleep during which vivid experiences occur. In this questionnaire study, we assessed the self-reported prevalence of hypnagogic states considering the frequency of experiences in different modalities. We also assessed the emotional quality and the vividness of the experiences. Moreover, we compared hypnagogic states to other phenomena, such as dreams, sleep paralysis, imagination, and extra-sensory perception in these measures. Hypnagogic states were reported by 80.2 % of 4456 participants and were more prevalent in women than men. Experiences were most often kinaesthetic and visual, and less often auditory, tactile, and olfactory or gustatory. Hypnagogic states were less prevalent than dreams and characterized by different modality profiles. However, they were similar to dreams in their emotional quality, the irritation they caused, and in their vividness. In conclusion, hypnagogic states are quite common.

Validity of the Persian version of the Munich ChronoType Questionnaire (MCTQIR)

PURPOSE

Currently, the most useful questionnaire for determining the chronotype is the Munich ChronoType Questionnaire (MCTQ). It determines chronotype based on sleep-wake behavior on workdays and work-free days and uses the mid-sleep time on free days (MSF), corrected for accumulated sleep debt over the work week to classify chronotype (MSFsc). Our study aimed at validating Persian version of the MCTQ.

METHODS

Participants completed the Persian version of the MCTQ, reduced Morningness-Eveningness Questionnaire (rMEQ), Epworth sleepiness scale (ESS), and demographic characteristics.

RESULTS

The study sample was comprised of 250 Iranian men and women (mean age 34 years, age range 30 to 58 years, 113 men). Results showed that there is a significant negative relationship between the components of MCTQ and rMEQ, and the strongest relationship related to the MSF index. The results also showed that MCTQ parameters were not significantly related to the ESS scale. Cut-off values of MSFsc for chronotype categories were determined by inter-quartile range (Q25% = 3.44, Q50% = 4.68, and Q75% = 5.75).

CONCLUSIONS

Like the MCTQ in other languages, the Persian version of the MCTQ is a reliable tool for assessing chronotype.

Impact of chronotype, insomnia symptoms, sleep duration, and electronic devices on nonrestorative sleep and daytime sleepiness among Japanese adolescents

OBJECTIVES

Nonrestorative sleep (NRS) and excessive daytime sleepiness (EDS) are important indicators of daytime dysfunction. Electronic media use before bedtime greatly affects adolescent sleep quality. However, few studies have examined factors associated with these symptoms. Therefore, we aimed to investigate the impact of chronotype, electronic device use before bedtime, and insomnia symptoms on NRS and EDS in Japanese adolescents.

METHODS

A web-based cross-sectional survey of 2067 adolescents was conducted in 2022 to mainly assess sleep-related issues (sleep duration, chronotype, insomnia symptoms, NRS, and EDS), time spent using electronic devices, physical activity, and mental health.

RESULTS

We analyzed data of 1880 adolescents (age, 16.4 ± 0.8 years; males, 56.7%). NRS and EDS prevalence rates were 54.9% and 39.4%, respectively. In multivariate analysis, evening chronotype [odds ratio (OR): 2.14, 95% confidence interval (CI): 1.58-2.89], difficulty initiating sleep (OR: 1.94, 95% CI: 1.43-2.64), <5 h sleep (OR: 1.77, 95% CI: 1.24-2.54), 5-6 h sleep (OR: 1.52, 95% CI: 1.20-1.93), and using electronic devices just before bedtime (OR: 1.48, 95% CI: 1.08-2.04) were associated with NRS. Evening chronotype (OR: 1.40, 95% CI: 1.07-1.82), early morning awakening (OR: 1.60, 95% CI: 1.02-2.50), using electronic devices just before bedtime (OR: 2.08, 95% CI: 1.48-2.93), and using electronic devices 30 min before bedtime (OR: 1.57, 95% CI: 1.07-2.29) were associated with EDS.

CONCLUSION

Chronotype may be an important factor influencing NRS and EDS. Discontinuing electronic device use at least 30 min before bedtime could benefit affected adolescents.

Effects of Chronotype and Social Jet-Lag on Neurocognitive Functioning

The chronotype, which reflects the circadian rhythm preferences of individuals in their daily activities and sleep-wake cycles, can be considered on a dimension of extreme morningism and extreme eveningism. Individuals with extreme morning and extreme evening chronotypes face many physical and psychological dangers due to accumulated sleep debt, short total sleep time and insufficient sleep efficiency. In extreme chronotypes, especially in extreme evening people, the social jet-lag effect due to the mismatch between social and circadian clocks is thought to exacerbate these dangers. More recent studies have suggested that social jet-lag and chronotype have many negative effects on cognitive functioning. The aim of this article is to review the impact of social jet-lag and chronotype on cognitive functioning.

Differences in Dietary Intake, Eating Occasion Timings and Eating Windows between Chronotypes in Adults Living with Type 2 Diabetes Mellitus

Chronotype studies investigating dietary intake, eating occasions (EO) and eating windows (EW) are sparse in people with type 2 Diabetes mellitus (T2DM). This analysis reports data from the CODEC study. The Morningness-Eveningness questionnaire (MEQ) assessed chronotype preference. Diet diaries assessed dietary intake and temporal distribution. Regression analysis assessed whether dietary intake, EW, or EO differed by chronotype. 411 participants were included in this analysis. There were no differences in energy, macronutrient intake or EW between chronotypes. Compared to evening chronotypes, morning and intermediate chronotypes consumed 36.8 (95% CI: 11.1, 62.5) and 20.9 (95% CI: -2.1, 44.1) fewer milligrams of caffeine per day, respectively. Evening chronotypes woke up over an hour and a half later than morning (01:36 95% CI: 01:09, 02:03) and over half an hour later than intermediate chronotypes (00:45 95% CI: 00:21; 01:09. Evening chronotypes went to sleep over an hour and a half later than morning (01:48 95% CI: 01:23; 02:13) and an hour later than intermediate chronotypes (01:07 95% CI: 00:45; 01:30). Evening chronotypes' EOs and last caffeine intake occurred later but relative to their sleep timings. Future research should investigate the impact of chronotype and dietary temporal distribution on glucose control to optimise T2DM interventions.

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

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

Sensation seeking, drinking motives, and going out mediate the link between eveningness and alcohol use and problems in adolescence

The present study was aimed at obtaining a more comprehensive understanding of the possible mediating factors in the morningness-eveningness → alcohol consumption relation. We explored the role of mediators such as sensation seeking, the frequency of going out in the evenings, and drinking motives. We tested the proposed mediation model via structural equation modeling based on cross-sectional research conducted among Hungarian adolescents and young adults (N = 1695, 42.5% male, Mage = 18.98, SDage = 1.89). The outcomes included the frequency of alcohol consumption and problematic drinking. Both alcohol consumption and problematic drinking were predicted in similar directions and magnitudes by sensation seeking, "going out," and coping drinking motives. However, eveningness still had a significant direct effect on alcohol consumption and problematic drinking after we controlled for sensation seeking, going out, and drinking motives. For problematic drinking, the possible role of drinking motives seems to be higher and more complex than it is for alcohol consumption. The mediators, such as sensation seeking, the amount of time spent out in the evenings, and drinking motives, can explain the eveningness → alcohol consumption relationship and should be targeted for alcohol prevention programs among evening-type adolescents.

Chronotype and lipid metabolism in Arctic Sojourn Workers

This study relates answers to the Munich Chronotype Questionnaire (MCTQ) and Pittsburgh Sleep Quality Index (PSQI) from Arctic Sojourn Workers (ASW) of Yamburg Settlement, 68° Latitude North, 75° Longitude East (n = 180; mean age ± SD; range: 49.2 ± 7.8; 25-66 y; 45% women) to Arctic Sojourn Work Experience (ASWE), age and health status. Chronotype, Mid Sleep on Free Days sleep corrected (MSFsc) and sleep characteristics of ASW were compared to those of age-matched Tyumen Residents (TR, n = 270; mean age ± SD; range: 48.4 ± 8.4; 25-69 y; 48% women), 57° Latitude North, 65° Longitude East. ASW have earlier MSFsc than TR (70 min in men, p < 0.0001, and 45 min in women, p < 0.0001). Unlike TR, their MSFsc was not associated with age (r = 0.037; p = 0.627) and was linked to a larger Social Jet Lag (+21 min in men; p = 0.003, and +18 min in women; p = 0.003). These differences were not due to outdoor light exposure (OLE): OLE on work (OLEw) or free (OLEf) days was not significantly different between ASW and TR in men and was significantly less in ASW than in TR women (OLEw: -31 min; p < 0.001; OLEf: -24 min; p = 0.036). ASWE, but not age, was associated with compromised lipid metabolism in men. After accounting for multiple testing, when corrected for age and sex, higher triglycerides to high-density lipoprotein ratio, TG/HDL correlated with ASWE (r = 0.271, p < 0.05). In men, greater SJL was associated with lower HDL (r = -0.204; p = 0.043). Worse proxies of metabolic health were related to unfavorable components of the Pittsburgh Sleep Quality Index in ASW. Higher OLE on free days was associated with lower systolic (b = -0.210; p < 0.05) and diastolic (b = -0.240; p < 0.05) blood pressure.

Effects of exogenous melatonin on sleep and circadian rhythm parameters in bipolar disorder with comorbid delayed sleep-wake phase disorder: An actigraphic study

The present study evaluates the effect of exogenous melatonin (exo-MEL) on sleep and circadian parameters in patients with bipolar disorder (BD) and delayed sleep-wake phase disorder (DSWPD). BD euthymic patients (n = 83, mean age = 45.13 ± 13.68, males 56%) were evaluated for chronotype (reduced Morningness-Eveningness Questionnaire [rMEQ]), sleep quality (Pittsburgh Sleep Quality Index), sleep and circadian parameters (actigraphic monitoring). Patients that fulfilled criteria for DSWPD (n = 25) were treated for three months with exo-MEL 2 mg administered approximately 4 h before the sleep onset time (SOT) actigraphically-determined at baseline. Sleep and circadian parameters at baseline (T0) and after the exo-MEL treatment (T1) were compared using paired Wilcoxon test. In patients that completed the treatment (n = 19), the rMEQ score increased between T0 (median = 8.0 [IQR = 7.0, 11.0]) and T1 (median = 13.5 [IQR = 9.3, 15.0], p-value = 0.006), the SOT was advanced between T0 (median = 00:55 [IQR = 00:25, 01:39] and T1 (median = 00:09 [IQR = 23:41, 01:04], p-value = 0.039), the sleep efficiency and total sleep time increased (T0: median = 84.4 [IQR = 81.3, 89.4]; T1 (median = 90.3 [IQR = 85.5, 92.9] %, p-value = 0.01, and T0: median = 7.20 [IQR = 6.15, 8.15]; T1: median = 7.7 [IQR = 7.0, 9.3] hours, p-value = 0.04, respectively). These results indicate that in BD with comorbid DSWPD, the self-reported chronotype, the sleep onset time, and sleep efficiency and duration were modified after a personalized treatment with exo-MEL, suggesting its potential efficacy in improving sleep patterns in BD. The absence of proper control groups and of treatment randomization constitute limitations of our study and further randomized controlled trials are required to confirm our results.

Diurnal Variation of Specific Tests' Performance and Related Psychological Aspects in Young Judo Athletes

Purpose: This study investigated the effects of time-of-day on judo athletes' performances and the associated psychological variables and perceived exertion following judo-specific tests. Methods: Twelve male judo athletes (age: 16 ± 1 years) performed in a randomized and counterbalanced order the special judo fitness test (SJFT), the judo physical fitness test (JPFT), the dynamic and isometric judogi chin-up tests in the morning (8:00 a.m), midday (12:00 p.m), and afternoon (5:00 p.m). Oral temperature and psychological variables [profile of mood state (POMS), Hooper questionnaire, total quality of recovery (TQR)] were assessed before and after the tests, and ratings of perceived exertion (RPE) and the physical activity enjoyment scale (PACES) were assessed only after the tests. Results: RPE score was higher in the morning compared to the afternoon after the JPFT (d = 0.38, p = .045). PACES after JPFT was higher in the morning compared to midday (d = 0.85, p < .001). The isometric and dynamic performances during chin-up tests were higher in the afternoon compared to the morning (d = 0.38, p = .048 and 0.047, respectively). Also, oral temperature was higher in the afternoon compared to the morning (d = 0.41, p = .050) and the midday (p = .047) for dynamic test, while TQR, well-being indices, and POMS did not differ according to time-of-day (p > .05). Conclusions: These results suggest that dynamic and isometric judo chin-up tests are time-of-day dependent with higher performance recorded in the afternoon than in the morning. However, performances in the JPFT and SJFT were not time-of-day dependent.

A daily examination of executive functioning and chronotype in bedtime procrastination

STUDY OBJECTIVES

Bedtime procrastination, or delays in bedtime not attributable to external obligations, is a behavioral tendency that undermines sleep and is conceptualized as a consequence of poor self-regulation. Prior studies investigating the mechanistic role of self-regulation in bedtime procrastination relied on cross-sectional methods and self-reported self-regulation. The present study examined the association between bedtime procrastination and both objective and self-reported executive functioning (EF) as indices of self-regulation, as well as the moderating role of chronotype, using methods that examined these associations at the daily level.

METHODS

A total of 273 young adult participants (78% female; Mage = 24.4) completed daily measures of objective EF (i.e., Stroop task), self-reported EF (i.e., self-reported cognitive, behavioral, and emotional regulation difficulties), and bedtime procrastination over 14 days, in addition to measures of chronotype. Multilevel models were constructed to examine the associations between bedtime procrastination and EF, as well as EF-chronotype interactions.

RESULTS

Poorer daily objective EF and self-reported behavioral regulation were associated with greater same-night bedtime procrastination. Additionally, poorer subjective cognitive and emotional regulation were associated with greater average bedtime procrastination across 14 days. Later chronotypes reported greater bedtime procrastination than early chronotypes.

CONCLUSIONS

The present study provides support for the association between EF and bedtime procrastination, but finds no evidence for the moderating role of chronotype in this association. Results suggest that some EF processes may be more relevant to bedtime procrastination than others. Current findings have implications for assessment and intervention for this consequential sleep-relevant behavioral tendency.

The moderating and mediating effects of personality on the association between morningness and well-being

Background

Morningness (morning-eveningness preference or chronotypes) and personality can be both associated with well-being, but few studies have directly compared these two constructs as correlates of well-being. Thus, the first purpose of this study was to test the effects of interactions between stable personality traits (temperaments) and morningness on well-being. Furthermore, personality factors are often composed of both stable biological factors (temperament) and socio-cultural factors (character), and little is known about personality interplay of temperament and character factors with respect to morningness and well-being. The second purpose of this study was therefore to examine the sequential mediating effects of temperament and character factors on the relationship between morningness and well-being.

Methods

The Composite Scale of Morningness, the Korean version of the Temperament and Character Inventory-Revised Short Version (TCI-RS), and the Satisfaction with Life Scale were used to measure morningness, personality dimensions, and well-being, respectively, in 287 Korean university students. Moderating and sequentially mediating effects of temperament and character traits were determined using Hayes' PROCESS macro in SPSS after controlling for sex and age.

Results

First, novelty-seeking (NS) and persistence (PS) temperaments have demonstrated the moderating effect in the association between morningness and well-being. The positive effects of morningness on life satisfaction increased with lower NS and PS, respectively. However, other temperaments such as harm avoidance (HA) and reward dependence (RD) have not shown the moderation in the relationship between morningness on well-being. Second, HA temperament and self-directedness (SD) character sequentially mediated the relationship between morningness and well-being. The combination of low scores of HA and high scores of SD have shown the positive effect on the relationship between morningness and well-being.

Discussion

This study demonstrated that both the interactions between temperaments and morningness, and combination of specific TCI-RS temperament and character traits play important roles in influencing the association between morningness and well-being. The significance of the mature SD character and its implications for well-being are discussed with limitation of the present study.

Circadian typologies and insomnia in individuals with internet gaming disorder comorbid with attention deficit/hyperactivity disorder

The alteration in circadian typology and insomnia were prevalent among both Individuals with IGD and those with attention deficit hyperactivity disorder (ADHD), the most comorbid psychiatric disorder of IGD. This study aimed to evaluate the relationships between circadian typologies, insomnia, and internet gaming disorder (IGD) and how ADHD affects this relationship. We recruited three groups of 69 young adults: an IGD group, a control group comprising age- and sex-matched nongamers, and a group of gamers without IGD through diagnostic interviews. The participants with IGD exhibited lower composite scale of morningness (CSM) scores and thus a higher eveningness preference In addition, the score of Pittsburgh insomnia rating scale-20-item version (PIRS_20) was significantly higher among those with IGD. The participants with IGD and ADHD exhibited lower CSM scores but higher PRIS_20 scores than the participants with IGD but without ADHD. The present findings indicate that participants with IGD exhibited a tendency of eveningness preference and experienced more severe insomnia. ADHD exacerbated the eveningness preference and insomnia of individuals with IGD. Close attention should be paid to sleep problems in individuals with IGD, particularly to those with ADHD.

Evidence for environment hypothesis: Cross-cultural measurement invariance of the composite scale of morningness across Bangladesh and Spain

Morningness-eveningness reflects individual differences in circadian functioning and is related to health and well-being. Cross-cultural comparison could facilitate understanding of the environmental factors affecting morningness-eveningness, which requires establishing cross-cultural validity of the relevant assessment tools. In this study, we applied the Composite Scale of Morningness (CSM) to Bangladeshi (n = 1015; 37.9% women) and Spanish (n = 1054; 73.2% women) university students (aged 18-27 years) to evaluate alternative factorial models of the CSM and to test its measurement invariance across cultures. Moreover, this study tested environment hypothesis, suggesting that higher average temperatures and lower latitudes would be related to greater morningness. From nine competing factorial models, a bifactor model with two specific factors (morning preference and morning affect) showed the best fit for both cultures. The two-factor bifactor model had full metric invariance with partial scalar and strict invariance across cultures. The Bangladesh-Spain comparison of the CSM scores revealed higher morningness in Bangladeshi students which supports the environment hypothesis. Overall, this research confirms that morningness-eveningness construct is perceived and interpreted similarly by the Bangladeshi and Spanish students. Importantly, this study highlights the effects of environmental factors including latitude and temperature on morningness-eveningness, and thus facilitates further cross-cultural morningness-eveningness research.

Circadian rhythms, gut microbiota, and diet: Possible implications for health

AIMS

Over the past years, interest in chrono-nutrition has grown enormously as the fundamental role of circadian rhythms in regulating most physiological and metabolic processes has become clearer. Recently, the influence of circadian rhythms on the gut microbiota (GM) composition has also emerged, as more than half of the total microbial composition fluctuates rhythmically throughout the day. At the same time, other studies have observed that the GM itself synchronises the host's circadian biological clock through signals of a different nature. Therefore, it has been hypothesised that there is a two-way communication between the circadian rhythms of the host and the GM, but researchers have only just begun to identify some of its action mechanisms. The manuscript aim is, therefore, to gather and combine the latest evidence in the field of chrono-nutrition with the more recent research on the GM, in order to investigate their relationship and their potential impact on human health.

DATA SYNTHESIS

Considering current evidence, a desynchronization of circadian rhythms is closely associated with an alteration in the abundance and functionality of the gut microbiota with consequent deleterious effects on health, such as increased risk of numerous pathologies, including cardiovascular disease, cancer, irritable bowel disease, and depression. A key role in maintaining the balance between circadian rhythms and GM seems to be attributed to meal-timing and diet quality, as well as to certain microbial metabolites, in particular short-chain fatty acids.

CONCLUSIONS

Future studies are needed to decipher the link between the circadian rhythms and specific microbial patterns in relation to different disease frameworks.

Physical activity and morningness: A helpful combination in improving the sleep quality of active Italian university students

University students are commonly described as having worsened sleep quality, especially when inactive and Evening-type (E-type) subjects. This study aimed to examine the interactions between physical activity and chronotype on sleep quality among a sample of active Sports Science university students. In November 2019, 433 participants (mean age: 19.7 ± 1.56 years; 70% males) completed the Pittsburgh Sleep Quality Index, the Godin-Shepard Leisure-Time Physical Activity Questionnaire (tertiles categorisation), and the Morningness-Eveningness Questionnaire. Females and E-type slept significantly worse than males and Neither-(N-types) and Morning-types (M-types), respectively. However, there were no significant differences in sleep quality based on physical activity levels. The three-way ANOVA revealed that sleep quality in N- and E-types appeared to be independent of physical activity, whereas M-types showed an improvement in sleep classification with increased physical activity. Moderation analysis indicated that physical activity significantly moderated the relationship between chronotypes and sleep quality. Specifically, M-types demonstrated a more pronounced improvement in sleep quality with increasing physical activity compared to the other chronotypes. In conclusion, M-type university students derived the greatest benefits from physical activity in improving sleep quality. Conversely, physical activity seemed to have a limited impact on sleep quality among active E-type university students.

The association between eveningness and autistic traits: Mediating effects of depression and insomnia

There is a lack of research on the relationships between autistic traits and morningness-eveningness. The current research explored associations between autistic traits (preferences for routine, difficulties with imagination, difficulties with social skills, fixations with numbers and patterns, and difficulties with attention switching) and morningness-eveningness, including the component of Morning Affect (alertness/energy upon awakening). The potential mediation effects of depression and insomnia were also tested. 163 adults (university students and general population) completed an online survey including questionnaire measures of autistic traits, morningness-eveningness, depression, and insomnia. Positive correlations were found between most autistic trait subcomponents, depression, and insomnia. The autistic trait of difficulties in attention switching was correlated with more eveningness and with less Morning Affect, but significant correlations were not observed with any other autistic trait. Depression mediated the relationship between eveningness and difficulties in attention switching. Although insomnia alone was not a significant mediator, when combined with depression in a serial mediator model, a significant mediation effect was shown. The current results suggest that greater eveningness may be related with the autistic trait of difficulties in attention switching possibly through the mechanism of increased insomnia and elevated risk for depression. These findings may potentially inform interventions.

The eveningness chronotype is associated with nightmare distress and dream recall: a cross-sectional study

Dreaming may be affected by sleep behavior; however, evidence of the effect of chronotypes on dreaming is limited. We investigated sleep patterns, dream recall, and nightmare distress according to chronotypes. This cross-sectional study retrospectively enrolled adult participants (age > 18 years) who visited a sleep laboratory between 2016 and 2021 and underwent standard polysomnography (PSG) and completed a self-reported questionnaire. Patients with major sleep disorders were excluded. Chronotypes and dreaming components were assessed using the Korean version of the morningness-eveningness questionnaire and a nine-item dreaming questionnaire (nightmare distress and dream recall), respectively. Among healthy participants without major sleep disorders, the eveningness chronotype correlated with better dream recall than the morningness and intermediate chronotypes. Participants with the eveningness chronotype were younger and more likely to be unmarried than those with the other chronotypes. No significant chronotype-based difference was observed in the subjective measurements of sleep quality, insomnia, daytime sleepiness, depression, and anxiety or in respiration and movement events on PSG. In multivariate linear regression analysis, the chronotypes were independently related to nightmare distress (b = - 0.296; p = 0.002) and dream recall (b = - 0.334; p = 0.002). The apnea-hypopnea index was associated with nightmare distress (b = - 0.209; p = 0.029) and dream recall (b = - 0.189; p = 0.044). Depression was positively correlated with nightmare distress (b = 0.450; p = 0.002). Dream recall was best in the eveningness group among healthy adults. Greater eveningness was associated with higher nightmare distress and better dream recall. Further research is needed to understand the role of chronotypes in dreaming.

Chronotype and Time of Day Effects on a Famous Face Recognition Task with Dynamic Stimuli

Chronotype and Time of Day (ToD) can modulate several aspects of cognitive performance. However, there is limited evidence about the effect of these variables on face recognition performance, so the aim of the present study is to investigate this influence. For this, 274 participants (82.5% females; age 18-49 years old, mean = 27.2, SD = 1.82) were shown 20 short videoclips, each gradually morphing from a general identity unfamiliar face to a famous face. Participants should press the spacebar to stop each video as soon as they could identify the famous face, and then provide the name or an unequivocal description of the person. Analysis of response times (RT) showed that evening-types recognised the faces faster than morning-types. Considering different ToD windows, the effect of chronotype was only significant in the 13h-17h and in the 21h-6h time-windows. Altogether, results suggest an advantage of evening-types on famous face recognition using dynamic stimuli with morning-types, being particularly slower during their non-optimal period.

Chronotype and athletes’ performance in sports: A narrative review

The circadian system is managed by the suprachiasmatic nucleus, which is also called a master clock, and peripheral clocks spread all over the body. A complex system of neuronal, hormonal, and autonomous signals coordinates these clocks. However, this narrative review aimed to discuss the influence of circadian rhythms on the athlete’s performance, rate of perceived exertion, resynchronization, and aerobic and anaerobic exercise. An adequately timed wake-up is believed to play an essential role in an athlete’s performance. Based on the literature, chronotype appears to correlate with ratings of perceived exertion and fatigue scores, and morning types are less fatigued in the morning. When chronotype was evaluated, fatigue and vigor had time-by-group interactions. Swimmers with morning-type profiles showed lower fatigue scores before the (06:30 hour) time test than before the (18:30 hour) time test, while those with neither-type profiles had similar fatigue scores in both sessions. Vigor scores were also higher in the morning types than in the neither-types (17.9±7.1) before the morning test and (15.6±5.5) before the evening test. Studies have also shown that exercise enhances aerobic capacity based on the day. However, several reasons can lead to conflicting evidence regarding the chronotype effect on performance studies. Thus, more research is needed regarding the chronotype effect on athletes’ performance and the impact of time of day on muscle strength.

Epigenome-wide association study identifies novel genes associated with ischemic stroke

BACKGROUND

DNA methylation has previously been associated with ischemic stroke, but the specific genes and their functional roles in ischemic stroke remain to be determined. Here we aimed to identify differentially methylated genes that play a functional role in ischemic stroke in a Chinese population.

RESULTS

Genome-wide DNA methylation assessed with the Illumina Methylation EPIC Array in a discovery sample including 80 Chinese adults (40 cases vs. 40 controls) found that patients with ischemic stroke were characterized by increased DNA methylation at six CpG loci (individually located at TRIM6, FLRT2, SOX1, SOX17, AGBL4, and FAM84A, respectively) and decreased DNA methylation at one additional locus (located at TLN2). Targeted bisulfite sequencing confirmed six of these differentially methylated probes in an independent Chinese population (853 cases vs. 918 controls), and one probe (located at TRIM6) was further verified in an external European cohort (207 cases vs. 83 controls). Experimental manipulation of DNA methylation in engineered human umbilical vein endothelial cells indicated that the identified differentially methylated probes located at TRIM6, TLN2, and FLRT2 genes may play a role in endothelial cell adhesion and atherosclerosis.

CONCLUSIONS

Altered DNA methylation of the TRIM6, TLN2, and FLRT2 genes may play a functional role in ischemic stroke in Chinese populations.

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

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

Chronotype and sensory-processing sensitivity: A cross-sectional survey

Here we examined the possibility of a relationship of sensory processing sensitivity (SPS) with chronotype in a German-speaking sample of N = 1807 (1008 female, 799 male) with a mean age of 47.75 ± 14.41 y (range: 18-97 y). The data were collected using an anonymous online questionnaire (Chronotype: one item of the Morning-Evening-Questionnaire, as well as typical bedtimes on weekdays and weekends; SPS: German version of the three-factor model ; Big Five: NEO-FFI-30) between 21 and 27 April 2021. Results. We found morningness to correlate with the SPS facet low sensory threshold (LST), while eveningness correlated to aesthetic sensitivity (AES) and marginally significant to ease of excitation (EOE). Discussion: The results show that the correlations between chronotype and the Big Five personality traits are not consistent with the direction of the correlations between chronotype and the SPS facets. The reason for this could be different genes that are responsible for the individual traits influence each other differently depending on their expression.

Chronotype as a predictor of scholar performance in a full-time middle school

The performance of day-to-day tasks, whether satisfactory or unsatisfactory, varies due to several environmental synchronizers, including the 24-hour light-dark cycle. For instance, human performance on physical and/or cognitive demanding activities reaches its peak during the day when the body temperature is at its circadian peak. Individual differences in the circadian peaks in temperature along with individuals' timing of sleep is referred to as chronotype. Here, we aimed to answer if (a) chronotypes affect the performance of students in a Brazilian full-time school with an early start time and if (b) there are differences in performance based on chronotype. We expected to find (a) a positive effect of the morning chronotype on the students' performance, particularly in subjects that take place in early morning; (b) while a negative effect of the evening chronotype in that same period. To address the effect of the chronotype on the students' scholar performance we build a Generalized Linear Mixed Model (GLMM). Results support the hypothesis that the students' performance is partially attributed to their chronotype. In particular, our findings shows that evening-type students are expected to have an increase of 0.038 (p ≤0.05) log counts on their performance in Portuguese classes compared to other chronotypes. Here we add evidence for the effect that individual chronotypes have on the students' performance in a Brazilian full-time middle school. Distinctive features of the studied Brazilian full-time middle school related to chronotypes are discussed.

Use of a Fitbit-like device in rats: Sex differences, relation to EEG sleep, and use to measure the long-term effects of adolescent ethanol exposure

BACKGROUND

Sleep difficulties and rhythm disturbances are some of the problems associated with adolescent binge drinking. Recently, animal models of alcohol-induced insomnia have been developed. However, studies in human subjects have recently focused not only on nighttime EEG findings but also on daytime sleepiness and disrupted activity levels as typically measured by activity tracking devices such as the "Fitbit." We sought to develop and test a Fitbit-like device (the "FitBite") in rats and use it to track rest-activity cycles following adolescent alcohol exposure.

METHODS

The effects of 5 weeks of adolescent ethanol vapor or control conditions were evaluated in 48 male and female Wistar rats using FitBite activity while intoxicated, and during acute (24 h post-vapor exposure) and chronic withdrawal (4 weeks post-vapor exposure). Data were analyzed using activity count and cosinor analyses. Fourteen rats were subsequently implanted with cortical electrodes, and data from the FitBite were compared with EEG data to determine how well the FitBite could identify sleep and activity cycles.

RESULTS

Female rats were generally more active than males, with higher circadian rhythm amplitudes and mesors (rhythm-adjusted means) across a 24-h period. There were significant correlations between EEG-estimated sleep and activity counts using the FitBite. When the rats were tested during intoxication after 4 weeks of ethanol vapor exposure, they had significantly less overall activity. Disruptions in circadian rhythm were also found with significant decreases in the circadian amplitude, mesor, and a later shift in the acrophase. At 24 h of ethanol withdrawal, rats had more episodes of activity with shorter durations during the daytime, when rats are expected to spend more of their time sleeping. This effect remained at 4 weeks following withdrawal, but circadian rhythm disruptions were no longer present.

CONCLUSIONS

A Fitbit-like device can be successfully used in rats to assess rest-activity cycles. Adolescent alcohol exposure produced circadian rhythm disturbances that were not observed after withdrawal. Fragmentation of ultradian rest-activity cycles during the light period was found at 24 h and 4 weeks after withdrawal and support data demonstrating the presence of sleep disturbance long after alcohol withdrawal.

Mindfulness, Subjective Cognitive Functioning, Sleep Timing and Time Expansion during COVID-19 Lockdown: A Longitudinal Study in Italy

During the COVID-19 lockdown, a distortion of time passage has been widely reported in association with a change in daily rhythm. However, several variables related to these changes have not been considered. The purpose of the present study was to assess the changes in dispositional mindfulness, time experience, sleep timing and subjective memory functioning. A longitudinal study was conducted on 39 Italian adults (53.85% males; 35.03 ± 14.02 years) assessing mindfulness, ad hoc questions of sleep habits during workdays and free days, chronotypes, subjective time experience, and memory functioning before (December 2019-March 2020) and during (April 2020-May 2020) the first Italian COVID-19 lockdown. Participants reported delayed sleep timing, a slowdown in the perception of the present time, a decrease of time pressure, and an increase in the feeling of time expansion/boredom. In addition to correlations between mindfulness, memory functioning, and subjective sleep duration during workdays, a mediation model showed that changes in the dispositional mindfulness determined a delay of bedtime during workdays through the mediation effect of increased feeling of time expansion/boredom. This finding highlighted the role of mindfulness in reducing the feeling of time expansion/boredom for regulating the sleep timing. The theoretical and practical implications of the findings are discussed.

Sleep Patterns, Eating Behavior and the Risk of Noncommunicable Diseases

Sleep is extremely important for the homeostasis of the organism. In recent years, various studies have been carried out to address factors related to sleep patterns and their influence on food choices, as well as on the onset of chronic noncommunicable diseases. The aim of this article is to provide a scientific literature review on the possible role of sleep patterns on eating behavior and the risk of noncommunicable diseases. A search was performed on Medline (PubMed interface) using several keywords (e.g., "Factors Influencing Sleep" OR "Sleep and Chronic Diseases"). Articles published between 2000 and the present date that relate sleep to cyclic metabolic processes and changes in eating behavior were selected. Changes in sleep patterns are increasingly detected today, and these modifications are mainly caused by work and lifestyle conditions as well as a growing dependence on electronic devices. Sleep deprivation and the resultant short sleep duration lead to an increased appetite via an increase in the hunger hormone (ghrelin) and a decrease in the satiety hormone (leptin). Nowadays, sleep is undervalued, and thus often impaired, with consequences for the performance of various body systems. Sleep deprivation alters physiological homeostasis and influences eating behavior as well as the onset of chronic diseases.

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

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

Revisiting Motor Imagery Guidelines in a Tropical Climate: The Time-of-Day Effect

(1) Background: Motor imagery (MI) is relevantly used to improve motor performance and promote rehabilitation. As MI ability and vividness can be affected by circadian modulation, it has been proposed that MI should ideally be performed between 2 p.m. and 8 p.m. Whether such a recommendation remains effective in a hot and humid environment, such as a tropical climate, remains unknown. (2) Methods: A total of 35 acclimatized participants completed a MI questionnaire and a mental chronometry test at 7 a.m., 11 a.m., 2 p.m., and 6 p.m. Visual (VI) and kinesthetic imagery (KI) abilities, as well as temporal congruence between actual walking and MI, were collected. Ambient temperature, chronotypes, thermal comfort, affect, and fatigue were also measured. (3) Results: VI scores were higher at 6 p.m. than at 7 a.m., 11 a.m., and 2 p.m., and temporal congruence was higher at 6 p.m. than at 7 a.m. Comfort, thermal sensation, and positive affect scores were higher at 7 a.m. and 6 p.m. (4) Conclusion: Data support greater imagery ability and accuracy when participants perceive the environment as more pleasant and comfortable. MI guidelines typically provided in neutral climates should therefore be adapted to tropical climates, with MI training sessions ideally scheduled in the late afternoon.

Sleep and chronotype influence aerobic performance in young soccer players

People can be classified into three chronotypes (CT): morning-type (M-type), Neither-type (N-type) and Evening-type (E-type). M-types perform better in the morning, E-types in the evening. It seems that bad sleep worsens physical performance. The impact of sleep and CT on specific sports and populations is unclear. Therefore, we wanted to assess agility, strength and endurance in young soccer players in relation to their sleep and chronotype. 58 players (13-19 years) were recruited. Sleep and CT were assessed by questionnaires. The physical trial was performed at 8:30 a.m. and 6:00 p.m., and included three tests to determine agility, strength and endurance. The sample was classified by CT as M-types (n = 11), N-types (n = 29) and E-types (n = 18). Furthermore, they were categorized as people with Good Sleep/Wake quality (GSW, n = 28) and people with Bad Sleep/Wake quality (BSW, n = 30). Comparing the three CTs in the aerobic test, M-types performed better in the morning (p = 0.01), while E-types in the evening (p < 0.001). GSW performed better than BSW (p = 0.019) in the aerobic test in the p.m. session. These results underline the difference in aerobic power between M-and E-types during the morning and evening session; moreover, they show a difference in p.m. aerobic performance according to sleep quality.

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

OBJECTIVES

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

METHOD

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

RESULTS

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

CONCLUSION

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

Evening types as determined by subjective and objective measures are more emotional eaters

OBJECTIVE

This study aimed to determine the association between being an evening type (ET; defined subjectively by the Morning-Evening Questionnaire or objectively by the dim-light melatonin onset [DLMO] timing) and reporting emotional eating (EE) behaviors.

METHODS

Cross-sectional analyses were conducted in 3964 participants (four international cohorts: ONTIME and ONTIME-MT [both Spain], SHIFT [the US], and DICACEM [Mexico]), in which chronotype (Morning-Evening Questionnaire), EE behaviors (Emotional Eating Questionnaire), and dietary habits (dietary records or food-frequency questionnaire) were assessed. Among 162 participants (ONTIME-MT subsample), additional measures of DLMO (physiological gold standard of circadian phase) were available.

RESULTS

In three populations, ETs presented with a higher EE score than morning types (p < 0.02); and they made up a higher proportion of emotional eaters (p < 0.01). ETs presented with higher scores on disinhibition/overeating as well as food craving factors and experienced these behaviors more frequently than morning types (p < 0.05). Furthermore, a meta-analysis showed that being an ET was associated with a higher EE score by 1.52 points of a total of 30 points (95% CI: 0.89-2.14). The timing of DLMO in the early, intermediate, and late objective chronotypes occurred at 21:02 h, 22:12 h, and 23:37 h, with late types showing a higher EE score (p = 0.043).

CONCLUSIONS

Eveningness associated with EE in populations with different cultural, environmental, and genetic backgrounds. Individuals with late DLMO also showed more EE.

Health Professionals' Chronotype Association with Salivary Cortisol and Occupational Stress in Neonatal Intensive Care Units

Burnout syndrome has been reported among health workers, particularly those working in critical areas, and is considered a significant public health problem. This study aimed to investigate the relationship between chronotype and work-related stress, as measured by salivary cortisol levels and burnout, among health professionals working in neonatal intensive care units. A cross-sectional study was conducted across four public hospitals in Fortaleza, Ceará, Brazil. Two hundred and fifty-six health professionals were administered the brazilian version of the Burnout Characterization Scale, the morningness-eveningness questionnaire, for chronotype, a sociodemographic questionnaire that included lifestyle habits and a salivary cortisol test. The results indicated that morning chronotype workers were significantly associated with the following: advanced age (p < 0.001), female gender (p = 0.032), married status (p = 0.014), and having children (p = 0.030) compared to those with evening and intermediate chronotypes. However, no significant association was found between signs of burnout syndrome and chronotype (p = 0.316). Participants whose work shift did not match their chronotype had significantly higher initial salivary cortisol levels (p = 0.013). The findings suggest that adapting working hours to an individual's biological rhythm can help mitigate potential negative effects on physical and mental health. Thus, it is recommended that professionals' working hours be adjusted accordingly.

The effect of TENS on sleep: A pilot study

BACKGROUND

Insomnia is the second most common neuropsychiatric disorder, but the current treatments are not very effective. There is therefore an urgent need to develop better treatments. Transcutaneous electrical nerve stimulation (TENS) may be a promising means of treating insomnia.

OBJECTIVE

This work aims to explore whether and how TENS modulate sleep and the effect of stimulation waveforms on sleep.

METHODS

Forty-five healthy subjects participated in this study. Electroencephalography (EEG) data were recorded before and after four mode low-frequency (1 Hz) TENS with different waveforms, which were formed by superimposing sine waves of different high frequencies (60-210 Hz) and low frequencies (1-6 Hz). The four waveform modes are formed by combining sine waves of varying frequencies. Mode 1 (M1) consists of a combination of high frequencies (60-110 Hz) and low frequencies (1-6 Hz). Mode 2 (M2) is made up of high frequencies (60-210 Hz) and low frequencies (1-6 Hz). Mode 3 (M3) consists of high frequencies (110-160 Hz) and low frequencies (1-6 Hz), while mode 4 (M4) is composed of high frequencies (160-210 Hz) and low frequencies (1-6 Hz). For M1, M3 and M4, the high frequency portions of the stimulus waveforms account for 50%, while for M2, the high frequency portion of the waveform accounts for 65%. For each mode, the current intensities ranged from 4 mA to 7 mA, with values for each participant adjusted according to individual tolerance. During stimulation, the subjects were stimulated at the greater occipital nerve by the four mode TENS.

RESULTS

M1, M3, and M4 slowed down the frequency of neural activity, broadened the distribution of theta waves, and caused a decrease in activity in wakefulness-related regions and an increase in activity in sleep-related regions. However, M2 has the opposite modulation effect.

CONCLUSION

These results indicated that low-frequency TENS (1 Hz) may facilitate sleep in a waveform-specific manner. Our findings provide new insights into the mechanisms of sleep modulation by TENS and the design of effective insomnia treatments.

Validation of the Munich Chronotype Questionnaire (MCTQ) in Chinese college freshmen based on questionnaires and actigraphy

The Munich Chronotype Questionnaire (MCTQ) was developed to determine an individual's chronotype, and it provides information about sleep and wake times separately for work and free days. However, the MCTQ has not been effectively verified using a large sample based on multiple questionnaires and actigraphy measures. Three sequential studies were conducted. Study 1 used a large sample (n = 1066) to investigate the chronotype of Chinese college freshmen and assess the validity of the MCTQ compared with the reduced Morningness-Eveningness Questionnaire (rMEQ), actigraphy, and other related questionnaires. Study 2 verified the MCTQ compared with a sleep diary. Study 3 examined the test-retest reliability of the MCTQ at the 2-year follow-up. The results showed that MCTQ parameters were significantly associated with rMEQ scores, the actigraphy-based mid-point of sleep, sleep quality, depression, and trait anxiety. In addition, all MCTQ variables were significantly related to the diary-based sleep mid-point. The test-retest reliability of the mid-point of sleep adjusted for sleep debt (MSFsc) and mid-point of sleep on free days (MSF) was acceptable. These results indicate that the MCTQ is a practical and efficient tool with good reliability. Its further development is important for the accurate assessment of chronotypes and clinical diagnoses of sleep.

Effects of chronotype on antidepressant treatment and symptoms in patients with depression: a multicenter, parallel, controlled study

AIM

To analyze the changes of chronotypes in patients with depression before and after treatment, and explore the effects of different chronotypes on antidepressant treatment and the dimensions of common symptoms in patients with depression.

METHODS

180 patients with depression were selected from 10 tertiary psychiatric hospitals in Zhejiang province, according to the scores of morningness-eveningness questionnaire (MEQ), the patients were divided into three groups: early-type group, middle-type group and late-type group. The 17-item Hamilton Depression Rating Scale (HAMD-17), Hamilton Anxiety Rating Scale anxiety Scale (HAMA), Snaith Hamilton Pleasure Scale (SHAPS), multidimensional fatigue inventory-20(MFI-20) and Pittsburgh sleep quality index (PSQI) were measured at baseline and at the end of the 2nd, 4th, 8th and 12th weeks, the variance analysis of repeated measures was used to analyze the change of each index in the study. The remission rate of depression at each time point was statistically analyzed.

RESULTS

Of the 180 patients included in the study, 26 were lost to follow-up, and 154 were finally included in the analysis. At baseline, 14.93%, 56.5% and 28.57% of the subjects were diagnosed as middle-late type, middle-late type and early-late type respectively, the total scores of Shaps and MFI-20 in the early-type group were higher than those in the late-type group and the middle-type group (p < 0.05). During the 12-week antidepressant treatment period, the time effect of PSQI, Shaps, MFI-20 and MEQ had interaction with different time groups (p < 0.05). During the treatment, the multiple symptom dimensions of depression were improved to different degrees, but the changing trend was not the same, and the recovery of the anhedonia was obviously delayed, in early-type patients, there are many symptoms such as loss of pleasure and sleep disorders. There was no significant effect on the remission rate of depression in different time type (p > 0.05) .

CONCLUSION

The disorder of chronotypes is common in patients with depression. The time effect of different time type on different symptom dimension of depression was affected, but the effect on remission rate of depression was not significant. To strengthen the management of biological chronotype rhythm in patients with depression may be of great significance in the treatment of depression.

Chronotype and quality of sleep in alpine skiers

Alpine skiing is among the most demanding sporting activities in terms of physical effort and mental workload. The aim of the study was to compare sleep quality and chronotype distribution between 84 highly trained alpine skiers and a control sample of 84 non-athletes matched by age and sex ratio. Quality of sleep was assessed by the Pittsburgh Quality of Sleep Index (PSQI), and chronotype was assessed by the Morningness-Eveningness Questionnaire (MEQ). Additional questions assessed sleep management during training or competitions. The results showed a marked skewed chronotype distribution towards morningness in alpine skiers (52.4% morning type, 42.8% intermediate, and 4.8% evening type) in comparison to the control group. The midpoint of sleep was significantly anticipated among alpine skiers. Differently from the previous literature that showed poor sleep quality and quantity in competitive athletes, the quality and quantity of sleep in alpine skiers was within the normal range in all the PSQI subcomponents.

Association between mobile phone addiction, chronotype and nonsuicidal self-injury among adolescents: A large-scale study in China

BACKGROUND

Nonsuicidal self-injury (NSSI) is a serious public health and clinical problem, particularly for adolescents, and may link to problematic smartphone use (PSU) and chronotype. This study examines the independent and interaction effects of PSU and chronotype on NSSI among adolescents and identified gender differences in these associations.

METHODS

A total of 21,357 students aged 11-19 were recruited using stratified cluster sampling across five representative provinces in China and completed standard questionnaires to record details of PSU, chronotype, and NSSI.

RESULTS

A total of 38.1 % of students reported having engaged in NSSI and 17.7 % had PSU. PSU and chronotype were significantly associated with NSSI among adolescents, and this relationship was stronger in females. Interaction analysis indicated that E-type and PSU were interactively associated with increased risks of NSSI.

CONCLUSION

The findings suggest that E-type and PSU can increase the risk of NSSI both independently and interactively. Therefore, they should be considered in intervention programs for NSSI, especially for females.