Sleep is crucial for children's health and eating habits. The decline in family meals has raised concerns about its impact on children. Previous research indicated associations between family meals and psychological health and dietary habits, but their relationship with sleep behavior is less understood. This study examined the association between family meals (breakfast and dinner), sleep patterns, and quality of life among Japanese preschoolers and elementary school students (1 to 3 grade). The cross-sectional study involved 6,177 children aged 3-8 years in Japan. Mothers completed an online survey on family meal habits, sleep patterns, and the KINDL-R questionnaire to assess quality of life. Results showed that family meals were associated with sleep behaviors and KINDL scores. Multiple regression analysis indicated that family breakfast was associated with earlier bedtime and wake-up time, shorter weekend sleep duration, reduced social jet lag, and a morning chronotype, as detected by the Munich ChronoType Questionnaire. Family dinners were linked to later sleep and wake-up times and an evening chronotype. Family breakfast and dinner were associated with higher KINDL scores, with dinner having a stronger positive impact. These findings underscore the significance of family meals in associating sleep patterns and quality of life among Japanese children.

The potential influence of circadian rhythm, seasonal variations, and alterations in meteorological parameters has been studied across various vascular events. However, there is a lack of evidence on the potential chronobiological impacts on thromboembolic events related to the most common peripheral aneurysm, the popliteal artery aneurysm (PAA). Data was obtained from a German PAA registry and the German Meteorological Service (Deutscher Wetterdienst). In this observational cohort study seasonality and chronobiology as well as associations with meteorological parameters of symptomatic PAA were investigated. In a multivariate logistic regression analysis, it was further analyzed whether meteorological parameters could distinguish asymptomatic from symptomatic patients in the registry. Of 1200 registered PAA,  = 142 PAA presented with acute limb ischemia between February 2011 and September 2022. More symptomatic patients (57.0%) presented to the hospital between January and June than in the second half of the year with a nadir in the fall season. Symptom onset was predominantly in the morning hours (39.5%). Atmospheric pressure and humidity values from the index dates diverged from a normal distribution showing a bimodal ("double-peak") configuration. Most patients developed symptoms after a reduction in temperatures compared to 1 or 2 d prior to the index date. However, we found evidence for an interaction between age and temperature difference, where the effects of a decreasing temperature fade with increasing age. Facing the complexity of individual-environment interactions, further investigations are needed to determine whether meteorological parameters are true risk modifiers or surrogates for seasonal differences and altered behaviors.

While links between certain chronotypes and poorer health outcomes have been well established in previous studies, few studies have examined the relationship between chronotype and cellular aging. Using data from the California Teachers Study (CTS), the present study evaluates the relationship between cellular aging and chronobiology through an analysis of leukocyte telomere length (LTL) and chronotype among 817 predominantly postmenopausal women with no history of cancer and occupations not associated with night-shift work. Unconditional logistic regression models were run to estimate odds ratios (ORs) for each chronotype category, adjusted for age, ethnicity, and smoking status. Analyses were then stratified by potential modifiers to assess whether results varied among specific subgroups within the sample. Women who reported being current evening types and evening types from teen years to now were significantly less likely to have short LTL compared to women who reported being current morning types or morning types from teen years to now (OR = 0.72; 95% CI = 0.53-0.98; OR = 0.57; 95% CI = 0.39-0.84). Our results suggest that women with no history of cancer who identify as evening chronotypes may undergo decreased cellular aging compared to women in the same population who identify as morning types. Further studies on populations of postmenopausal women are warranted.

Circadian rhythm-related individual differences such as chronotypes (morningness/eveningness) are associated with mental health though not elucidated in circadian-disrupted populations such as flight attendants. International flight attendants ( = 288) aged 21 to 55 (70.8% female, 76.4% white) completed an online survey assessing chronotypes, attachment, depression, and anxiety to investigate the associations between these variables. Results showed a prevalence of intermediate (41.6%) and evening types (40.6%). Evening chronotype was associated with and significantly predicted depression but not anxiety. Individuals who scored higher in attachment anxiety or avoidance had higher levels of depression and anxiety. Exploratory mediation showed that attachment avoidance partially mediated the relationship between anxiety and depression. Overall, chronotypes and attachment are implied as transdiagnostic factors for mental health outcomes and highlighted using a Chrono-Attachment Health Model. Further research is needed to confirm these findings among flight attendants and shift workers.

Sleep quality, chronotype, and mood may be closely interconnected processes. Typically, such constructs are measured independently, leaving out important information regarding their intrinsic relationships. The Sleep, Circadian Rhythms, and Mood (SCRAM) questionnaire is a promising tool for measuring sleep, chronotype, understood as diurnal preference, and depressive symptomatology, and the interrelationships between them. Anxiety has also been linked to sleep quality, chronotype, and depression, but there is currently no scale that measures these constructs together. This study aims to validate a revised version of the SCRAM questionnaire (rSCRAM), incorporating items to measure anxious mood. 486 Italian participants were involved in two studies. In Study 1, principal component analysis (PCA) identified representative anxiety elements from validated questionnaires. In Study 2, after adding the anxiety elements, exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) established a 4-factor, 16-item model. The rSCRAM demonstrated excellent psychometric properties: high internal consistency (α = 0.72-0.90) and a strong test-retest reliability of the scales over 2 weeks ( = 0.73-0.82), a high correlation for convergent validity, and low correlations for divergent validity. The rSCRAM questionnaire measures the constructs for which it was created and revised. Including the anxiety scale enhances its utility in assessing mental health constructs within a single instrument.

Melatonin is produced in the pineal gland under very tight control through the influences of light and the suprachiasmatic nucleus. As such, melatonin circulates in the blood at levels <3 pg/ml during the day and is only actively secreted at night reaching levels of approximately 100 pg/ml. As a consequence of binding to plasma proteins, free melatonin appears in saliva at approximately one third the plasma concentration. Measurement of melatonin is technically challenging because of these very low concentrations and while a number of commercial immunoassay kits are available and mass spectrometry assay methods have been published, not all are fit for purpose and can lead to unreliable conclusions. In this review I discuss the aspects of pineal melatonin production that saliva melatonin reflects, the factors influencing melatonin production or metabolism, saliva collection and analysis methods. Examples are provided of the appropriate use of saliva melatonin measurements; Dim Light Melatonin Onset (DLMO) assessment, impact of light on melatonin and the monitoring of rhythms prior to specific treatments. Examples of inappropriate use of saliva melatonin measurements are also provided including the use of poorly validated assays, morning saliva collections, attempts to stimulate melatonin, and linking specific illnesses to saliva melatonin levels.

Plasma glucose spikes affect cardiac autonomic modulation resulting in a decrease of heart rate variability (HRV). We hypothesize that a later chronotype or a higher morning plasma melatonin level is associated with larger decreases of HRV following an early high glycaemic index (GI) breakfast. In persons with an early ( = 21) or a late ( = 15) chronotype who consumed a high GI breakfast at 7 a.m. glucose data were continuously monitored. Time domain HRV parameters were calculated from blood volume pulses derived by wireless wrist worn multisensor. HRV changes (values after minus values before breakfast) were associated with chronotype by multivariable linear regression adjusted for age, sex and baseline levels. Morning plasma melatonin levels were determined from samples drawn on the run-in day. Time domain parameters indicate a higher HRV before high GI breakfast in both chronotypes. A later chronotype tended to be associated with smaller decreases of mean interbeat intervals ( = 0.08) only; no associations were seen with morning melatonin levels. This exploratory analysis in a small sample provides a first indication that in young healthy adults later chronotype might be associated with reduced ANS activation following a high GI breakfast. Future studies should elucidate whether this indicates parasympathetic or sympathetic inhibition.

Anxiety is being increasingly linked to circadian rhythms, including chronotype, in addition to its intricate links with sleep quality. Emotional competence is thought to be a strong predictor of wellbeing and mental health. This study aimed to examine whether a combination of chronotype, sleep quality, and intrapersonal emotional competence can predict anxiety in emerging adults (aged 18-29), who have the greatest prevalence of adult anxiety. One hundred and seventeen participants completed self-report measures of chronotype, sleep quality, emotional competence, and anxiety. A multiple linear regression, with anxiety as the criterion variable, showed that while all predictors were significant, sleep quality was the strongest predictor of anxiety. A later chronotype, poorer sleep quality and lower intrapersonal emotional competence were related to higher anxiety. Thus, integrating intrapersonal emotional competence and chronotype considerations into interventions may address the interplay between sleep quality and anxiety in emerging adults more effectively.

Actigraphy provides a unique method for objectively measuring sleep activity patterns, but confusion remains about how to use actigraphy data to determine chronotype. To determine the most suitable parameter, this study made a systematic comparison of actigraphy-derived parameters: the average midpoint of sleep of all record days (aMS-acti), cosine parameter (Bathyphase), and non-parametric parameter (L5-mid) in terms of the consistency with subjective chronotype parameters, test-retest reliability, and external validity. More importantly, we proposed multiple Munich Chronotype Questionnaire (MCTQ)-based actigraphy parameters: considering the difference between weekday (MSW-acti) with weekends (MSF-acti) and the sleep debt (MSFsc-acti). The study collected 5 days of actigraphy and scale data from 1,055 young adults, 138 of whom participated in the retest 2 years later. The results showed that, in terms of consistency with subjective chronotype, aMS-acti generally performed better than other actigraphy parameters. In addition, aMS-acti had the highest test-retest reliability and was more closely related to the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), and Self-Rating Depression Scale (SDS). The results suggest that the simplest parameter (aMS-acti) is superior to traditional cosine and non-parametric parameters and MCTQ-derived parameters for short-term assessment of chronotype.

Models of shift work and health suggest that individual differences in circadian rhythm characteristics may moderate the relationship between night shift work and injury, but this argument has not been directly tested. In this study, we tested the efficacy of two circadian rhythm characteristics-vigour and flexibility-as moderators of the path between shift work and injury. In addition, we aimed to replicate the association between vigour, flexibility, and alertness by time of day, and the measurement properties of the Circadian Type Inventory. We recruited 401 healthcare workers from Australia and Great Britain. After controlling for confounding variables, the results showed that vigour moderated the association between shift work and injury. Participants with values of vigour at the mean ( = 0.5120,  < 0.0013, 95% CI = [0.2018, 0.8223) and one standard deviation below the mean ( = 0.9048,  < 0.0001, 95% CI = [0.4648, 1.3447] reported significantly more injuries. No moderation was found for flexibility. Significant differences in alertness by time of day were observed in participants with higher levels of vigour compared to lower levels of vigour. No differences in alertness were observed for the flexibility scale. These results indicate that vigour may be a robust indicator of shift work tolerance. We replicated the posited two-factor structure of the Circadian Type Inventory, found the scales to have good reliability, and established for the first time, criterion-related validity for the vigour scale.

Temporal patterns of eating and diet composition are influenced by factors including circadian preference (chronotype) and work schedule, yet their combined influence is unknown. We investigated relationships between chronotype, temporal eating patterns (duration of eating window (DEW), time of first (FEO) and last (LEO) eating occasions), and diet composition on workdays (WD) and work-free days (FD). Non-shift workers ( = 39) completed the Chrononutrition Questionnaire (CNQ) (age: 38.8 ± 17.2 years, BMI: 24.8 ± 4.78 kg/m, 82% female) that captures chronotype and temporal eating patterns, and returned work diaries (work schedule) and 7-day food diaries (diet composition) after 2 weeks. Twenty-nine participants provided dietary data for at least two work and work-free days. Later chronotype was associated with later FEO on FD (r = 0.45,  = 0.004), later LEO on FD (r = 0.60,  < 0.001) and WD (r = 0.61,  < 0.001), and longer DEW on WD (r = 0.37,  = 0.024). Relationships between chronotype and diet composition were small. Later FEO was associated with higher % energy from fat (r = 0.39,  = 0.043) and lower fibre intake (r = -0.69,  < 0.001) on WD. Later chronotypes had shorter and later eating windows on FD than WD. Our findings suggest that relationships between chronotype, temporal eating patterns, and diet composition differ by day type. Further investigation may inform dietary strategies that are day-specific.

This study investigated whether sleep-specific (e.g. chronotype) and traditional (e.g. resilience) protective factors were associated with reduced shift work disorder (SWD) risk and explored their role as moderators in the relationship between SWD risk and health. Shift workers ( = 126) participated in a cross-sectional study evaluating SWD risk (i.e. low vs. high; SWD-screening Questionnaire), mental health (Patient Health Questionnaire-9; Generalized Anxiety Disorder Questionnaire-7), physical health (Subjective Health Complaints Inventory), sleep (Pittsburgh Sleep Quality Index; Insomnia Severity Index; Epworth Sleepiness Scale), and protective factors (Resilience Scale; Social Provisions Scale; Survey of Perceived Organizational Support; Short Impulsive Behavior Scale; Circadian Type Inventory; reduced-Morningness-Eveningness Questionnaire). Logistic regressions revealed lower sleep languidity was associated with reduced odds (OR = 0.88 [0.79,0.96]) for having high SWD risk. Multiple regression analyses showed in shift workers with high social support or morningness, having high SWD risk was not associated with increased depression symptoms, or insomnia severity and poor sleep quality, respectively. Finally, in those with high or medium levels of perceived organizational support, high SWD risk was not associated with increased gastrointestinal and allergy complaints. Longitudinal research with larger samples is needed to confirm the moderating role of protective factors in the relationship between SWD risk and health.

During the COVID-19 pandemic, studies reported that restricted living conditions were associated with worse subjective sleep quality. This effect might have been caused by reduced light exposure during lockdowns. We investigated light exposure levels, subjective and objective sleep and physical activity levels in older adults during restricted and free-living conditions after the pandemic. Ninety-one participants (62.7 ± 8.4 years) recruited from the community using social media with 44 participants (63.4 ± 8.9 years) completed follow-up during free-living conditions. Participants wore an actigraphy device and completed sleep diaries for 7 days during each condition. Light values were extracted in hourly bins across the 24-h period and objective and subjective sleep were compared between the conditions. There was an increase in mean 24-h light exposure during restricted-living (1103.7 ± 1024.8 lux) compared to free-living (803.0 ± 803.6 lux;  < 0.001). This was partially related to participants spending 18 min more in bright light conditions (>1,000 lux) during wakefulness in restricted living (2.6 ± 1.9 h) compared to free-living (2.3 ± 2.0 h;  = 0.036). Despite differences in light exposure, there were no significant differences in objective and subjective sleep parameters between the two conditions. More research is required to better understand behaviours related to light exposure and how this may impact on sleep.

Numerous studies have shown the influence of the moon cycle on biological functions in farm animals, suggesting that predicting calving distribution could enhance survival rates by improving management practices in animal production. This study builds on previous research by examining the impact of the lunar cycle on calving frequency, gestation length, birth weight, and calf sex in artificially inseminated cows. We analyzed 121,276 records from dual-purpose crossbred cows across 36 farms along the western margin of Lake Maracaibo basin, Venezuela. The lunar cycle was divided into 30 periods of 0.984 days each and further categorized into four phases: 1) 1.97 days around the new moon; 2) 12.8 days during the crescent phase; 3) 1.97 days around the full moon; and 4) 12.8 days during the waning phase. Data were analyzed using a logistic regression and the general linear model in SAS, comparing proportions and means with contrast and general linear model tests, respectively. There was no association between the lunar cycle and the sex of calves. However, calvings distribution across the lunar month showed notable peaks 2 days around both the new and full moons, a pattern consistent regardless of the number of calvings or gestation lengths. In addition, significant differences were observed between the days surrounding the new (1) and full (3) moons compared to the other lunar phases (2 and 4). Moon cycle also influenced gestation length and calf birth weight. This study expands previous findings and demonstrates that the lunar cycle consistently affects certain reproductive traits in inseminated dual-purpose cows, including gestation length, calf birth weight, and calving distribution, with practical implications for cattle operations.

Chronotype is the temporal behavior of an organism. Social jetlag, fear of missing out (FoMO), and phubbing have received increasing attention recently and are closely related to sleep quality. This study aimed to explore the relationship between chronotype and these factors and their effects on sleep quality among medical students. The FoMO scale, phubbing behavior assessment scale, morning-evening questionnaire, Pittsburgh sleep quality index, social jetlag questionnaire, and online sociodemographic data form were filled out by 537 students participating in the study. The average age of participants was 21.34 ± 1.38 years; 43.2% were male, and 56.8% were female. The majority (66.7%) had an intermediate chronotype, 20.9% an evening type, and 12.5% a morning type. Evening chronotypes exhibited the highest levels of social jetlag, daily internet/phone use, and the poorest sleep quality and daily functioning. Women reported significantly higher levels of FoMO ( < 0.001), phubbing ( = 0.020), and daytime dysfunction ( = 0.005). Multiple regression analysis showed poor sleep quality was associated with high FoMO, high phubbing, high levels of social jetlag, and evening chronotype. Additionally, daytime dysfunction was associated with female gender, poor sleep quality, high FoMO, and high levels of phubbing ( < 0.001, F = 16.128, R = 0.221). These results suggest that individuals with an evening type may be susceptible to social interaction, social media use, and sleep patterns, which may negatively affect sleep quality. It has also been determined that females may be at greater risk for FoMO and phubbing. Evaluation of individuals' chronotypes will be an essential step in treating behavioral addictions such as social media, screen, and smartphone addiction.

The Morningness-Eveningness-Stability-Scale-improved (MESSi) assesses three components of circadian functioning: Morning Affect (time to fully awaken), Eveningness (orientation/preference for evening activity), and Distinctness (amplitude of diurnal variations in functioning). Following the original German version, translations of the MESSi (including Spanish, Turkish, and Chinese) have been validated, but validity evidence for the English-language version has been lacking. The current study tested the factor structure, internal consistency, and predicted correlations of the English-language MESSi. A sample of 600 adults from an online recruitment platform (aged 18-78, mean = 41.31,  = 13.149) completed an online survey including the MESSi, reduced Morningness-Eveningness Questionnaire (rMEQ), Sleep Inertia Questionnaire (SIQ), and measures of personality and depressive symptoms. Exploratory factor analysis exactly reproduced the three-component structure of Morning Affect (MA), Eveningness, and Distinctness, with all items loading strongly on their respective component. Confirmatory factor analysis of this structure showed acceptable fit. The three subscales showed good internal consistency and replicated previously reported correlations with depressive symptoms, sleep inertia, sleep quality, and personality. Further factor analysis combining the items of the MESSi, rMEQ, and SIQ replicated a previously found seven-factor structure: Cognitive, Emotional, and Physiological sleep inertia (SI), Responses to SI (including one MA item); Duration of SI (one SIQ item, 3/5 MA items); Morningness-Eveningness (MESSi Eveningness items, plus 3/5 rMEQ items); Distinctness (5/5 MESSi items). In conclusion, the English-language MESSi shows sound psychometric properties, but Morning Affect may be more suitably characterised as a measure of sleep inertia duration, rather than morningness preference.

Chronotherapy is the timing of medications to circadian rhythms to optimize beneficial and minimize adverse outcomes. We reviewed the US Online Prescribers' Digital Reference for the specified administration schedule of medications prescribed to manage coronary heart disease (CHD) and its major risk factors. For arterial hypertension, dosing of terazosin and guanfacine is recommended in the evening and thiazide, thiazide-like, and sulfonamide diuretics morning; Verapamil (Verelan®) morning, its "PM" formulation evening, and long-acting diltiazem (Cardizem® LA), per clinical goal, morning or evening. Most hyperlipidemia medications are recommended in the evening. Many hyperglycemia medications are intended for morning ingestion, but, when indicated, some may be prescribed in unequal doses or intervals. For obesity, administration of appetite suppressant psychostimulants and sympathomimetics is stipulated for morning ingestion. Sleep insufficiency medications are to be taken before bedtime. For tobacco dependence, transdermal nicotine patch application is recommended in the morning, and bupropion early, but not late, during the wake span. For alcohol dependence, disulfiram is intended for morning ingestion. For thromboembolism prophylaxis, factor Xa inhibitor rivaroxaban is recommended at dinner and low-dose acetylsalicylic acid before bedtime. Medications for angina pectoris and edema of congestive heart failure are stipulated for morning administration. Overall, >200 medications prescribed to manage CHD and its risk factors qualify as chronotherapies.

This study aimed to investigate the relationship between chronotype, video game addiction, and sleep quality in school-age children using structural equation modeling. It was performed using structural equation modeling, with 545 secondary school students in northern Turkey meeting the inclusion criteria. Data were collected through face-to-face interviews utilizing the Personal Information Form, the Morningness Eveningness Scale for Children (MESC), the Video Game Addiction Scale for Children (VASC), and the Sleep Quality Scale. The findings revealed that the average video game addiction score of children was 55.22, which was associated with poor sleep quality and efficiency. Additionally, chronotype was found to mediate the relationship between video game addiction and both sleep quality (β = 0.024;  < 0.001) and sleep efficiency (β = -0.068;  < 0.001). The model was found to be close to acceptable levels for the variables according to the fit indices.

Circadian rhythms are important biological contributors to health. Rest activity rhythms (RAR) are emerging as biomarkers of circadian behavior that are associated with chronic disease when abnormal. RAR have not yet been characterized in chronic kidney diseases (CKD). Leveraging the National Health and Nutrition Examination Survey (2011-2014), patients with CKD ( = 1114; Mean [95% CI]: Age, 50 [58-61] y; 52% female) were compared with non-CKD individuals ( = 5885; Age, 47 [46-48] y; 52% female). Actigraphy data were processed for RAR parameters including rhythmic strength (amplitude), the rhythm adjusted mean (mesor), the timing of peak activity (acrophase), activity regularity (inter-daily stability), and activity fragmentation (intra-daily variability). Cox regression was performed to assess RAR parameters for the prediction of all-cause mortality. Compared to non-CKD adults, patients with CKD had a lower rhythmic amplitude and mesor, and exhibited greater fragmentation and less day-to-day stability in RAR (p 0.001). Among CKD patients, a lower rhythmic amplitude (HR [95% CI]: 0.88 [0.82-0.96];  < 0.001), a lower rhythm adjusted mean (0.87 [0.81-0.95];  = 0.002), and a higher daily activity fragmentation (1.87 [1.10-3.18];  = 0.023) were associated with an increased risk of all-cause mortality. Patients with CKD showed dampened rhythmic amplitudes and greater fragmentation of activity that were associated with a higher risk of all-cause mortality. These findings demonstrate a relationship between circadian disruption and prognosis in patients with CKD.

The aim of the current study is to investigate whether the time of day at which exercise is performed affects metabolic, glucose and insulin responses to exercise in adults. Databases were searched for randomised controlled (parallel and crossover) trials with participants aged from 18 to 65 year, an intervention of any exercise carried out at a specific time of the day and compared to any exercise carried out at a different time of the day. From 2458 screened articles, 12 studies were included in the systematic review of which 5 studies were included in the meta-analyses which compared 24 h continuous glucose monitoring (CGM) data, between morning and afternoon/evening exercise, on the day exercise was performed (SMD = 0.12 [-0.22-0.46]  = 0.76) and the day after exercise (SMD = -0.02 [-0.36-0.33]  = 0.94. Similar findings were observed in the wider systematic review with a general unclear risk of bias and a low certainty in these data. The results indicate that there is no clear effect of the time of the day on metabolic responses to exercise and exercise at any time of day should be the goal of public health strategies.

The aim of this study was to explore whether National Football League (NFL) coaches show variation in their decision-making on fourth down when traveling through time zones. Data from visiting teams in games from 20 seasons (2000-2020) of the NFL were retrieved from online sources ( = 5360 games). Decision-making was measured with the percentage of offensive plays on fourth down. A factorial ANCOVA was done to verify whether travel direction had an impact on fourth downs in evening games, while controlling for the seasons. A moderation analysis was computed to verify whether the time of game moderates the relationship between longitudinal distance traveled and decisions on fourth downs. Results showed that in evening games, coaches in teams traveling westward called more offensive plays on fourth down, compared to when they traveled in any other direction. Results from the moderation analysis showed that only in evening games, further westward longitudinal degrees traveled predict more fourth downs. For the first time, this study offers insight that circadian misalignment may not only affect player performance but also influence coaching decisions in professional sports. These results beg the question whether other aspects of coaching or staff decisions show circadian variations in professional sports.