Midsleep Point Research Articles

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

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

Relationship between Telework Jetlag and Perceived Psychological Distress among Japanese Hybrid Workers.

Social jetlag is associated with physical and mental health problems. With the increased popularity of telework, we investigated a specific form of social jetlag that we termed "telework jetlag". This study aimed to clarify the relationship between telework jetlag-the difference in sleep and wake-up times between in-office and telework days-and mental health problems among Japanese hybrid workers. A cross-sectional study was conducted with 1789 participants from October to December 2021 using an online-based questionnaire. Telework jetlag, defined as the difference in the midsleep point between in-office and telework days, was investigated using two groups according to telework jetlag-those lagging <1 h versus ≥1 h. We used the six-item Kessler Scale as a nonspecific psychological distress scale for the outcome. Telework jetlag was significantly associated with psychological distress, and the ≥1 h group had a higher risk (odds ratio: 1.80) of developing high psychological distress (HPD) than the <1 h group in the multivariate analysis. Since most teleworkers are forced to have a hybrid work style that mixes going to work and teleworking, telework jetlag must be addressed to maintain the health of teleworkers.

Association of residential greenness with chronotype among children

BackgroundThe association between residential greenness and chronotype remains unclear, especially among children. The current study aimed to explore the associations between residential greenness and chronotype parameters in children and examine potential pathways for these associations. MethodsIn this cross-sectional study, 16,421 children ages 3–12 were included. Two satellite-derived vegetation indices, i.e., the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI), were used to estimate residential greenness. The mid-sleep point on a workday (MSW) and the mid-sleep point on free days (MSF) were considered. And mid-sleep time on free days adjusted for sleep debt (MSFsc) was used as an indicator of chronotype. In addition to multivariable linear regression models, subgroup analyses were conducted to explore effect modifiers, and mediation analyses were used to explore possible mediating mechanisms of air pollutants underlying the associations. ResultsAn interquartile range (IQR) increase in both NDVI500-m and EVI500-m was significantly associated with an earlier MSFsc of −0.061 (95 % confidence interval (CI): −0.072, −0.049) and −0.054 (95 % CI: −0.066, −0.042), respectively. Non-linear dose response relationships were discovered between greenness indices and MSFsc and MSF. The results of stratified analyses showed the effect of residential greenness on MSW was stronger among primary school children and individuals with higher household income than among kindergarten children and those with lower household income. The joint mediation effects of PM2.5, PM1, PM10, NO2, and SO2 on the associations of NDVI500-m and EVI500-m with MSFsc were 89.6 % and 76.0 %, respectively. ConclusionsHigher levels of residential greenness may have beneficial effects on an earlier chronotype in the child population, by reducing the effects of air pollutants, especially PM2.5. Our research hopes to promote the deployment of green infrastructure and healthy urban design strategies.

0737 Age, menstrual phase, and circadian preference impact sleep in menstruating individuals

Abstract Introduction An eveningness chronotype is generally associated with reduced sleep continuity and quality, as well as social jetlag. Changes in hormones and menstrual phase similarly impact sleep, although research on the chronobiological effects of these changes are equivocal. This study aimed to examine the role of menstrual cycle in daily self-report and actigraphy-assessed sleep in two consecutive menstrual cycles. Methods Participants (n=51; 43% Caucasian), 18-35 years (23.67±4.68) completed actigraphy and daily sleep diaries over two menstrual cycles (m days=51.29). Four menstrual phases were identified via dates of menstrual bleeding and urinary ovulation testing: perimenstrual (±3 days of bleeding), mid-follicular, periovulatory, and mid-luteal. Relationships between menstrual phase and sleep parameters were estimated using multistep hierarchical linear modeling. Subjective and objective measures yielded the following sleep variables: Total Wake Time (TWTsub and TWTobj), Sleep Efficiency (SEsub and SEobj), and mid-sleep point (MSP). Participants completed the Morning-Eveningness Questionnaire (MEQ) at baseline. Results Mean cycle length was 28.61 days±2.69. Age was significantly associated with TWTobj (r=-.32, p &amp;lt;.001); SEobj (r=.34, p &amp;lt;.001), and MSP (r=-.42, p &amp;lt;.001) such that older participants had shorter TWT, higher SE, and earlier MSP. TWTobj was 4-7 minutes lower during the mid-follicular (61.54±3.37) and mid-luteal phases (63.11±3.29) compared to the perimenstrual phase (67.54±3.37; p &amp;lt;.001). SEobj was higher in the mid-luteal phase (82.50±0.79) vs. the perimenstrual phase (80.71±0.82, p =.006). Perimenstrual women reported 8-16 minutes longer awake (TWTsub=52.23±5.01, p &amp;lt;.001) and had 1-3% reduction in SEsub (89.70±0.10, p &amp;lt;.001). MEQ negatively predicted TWTobj (p=.004) and SEobj (p=.003), but did not vary across menstrual phase. In morning-type individuals, TST was significantly higher in the periovulatory (b =1.81, p=.01) and mid-luteal phases (b=2.03, p&amp;lt;.001) compared to the perimenstrual phase. Conclusion With increasing age, women experienced reduced time awake, higher sleep efficiency, and earlier sleep timing. Eveningness predicted greater total wake time and lower sleep efficiency. With menstrual phase considered, disturbed sleep was highest in the perimenstrual phase and women reporting a stronger preference for eveningness reported shorter TST during the perimenstrual phase. These findings highlight the importance of considering the menstrual cycle in the sleep health of menstruating individuals. Support (if any)

Association of meal timing with body composition and cardiometabolic risk factors in young adults

PurposeTo investigate the association of meal timing with body composition and cardiometabolic risk factors in young adults.MethodsIn this cross-sectional study participated 118 young adults (82 women; 22 ± 2 years old; BMI: 25.1 ± 4.6 kg/m2). Meal timing was determined via three non-consecutive 24-h dietary recalls. Sleep outcomes were objectively assessed using accelerometry. The eating window (time between first and last caloric intake), caloric midpoint (local time at which ≥ 50% of daily calories are consumed), eating jetlag (variability of the eating midpoint between non-working and working days), time from the midsleep point to first food intake, and time from last food intake to midsleep point were calculated. Body composition was determined by DXA. Blood pressure and fasting cardiometabolic risk factors (i.e., triglycerides, total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, and insulin resistance) were measured.ResultsMeal timing was not associated with body composition (p > 0.05). The eating window was negatively related to HOMA-IR and cardiometabolic risk score in men (R2 = 0.348, β = − 0.605; R2 = 0.234, β = − 0.508; all p ≤ 0.003). The time from midsleep point to first food intake was positively related to HOMA-IR and cardiometabolic risk score in men (R2 = 0.212, β = 0.485; R2 = 0.228, β = 0.502; all p = 0.003). These associations remained after adjusting for confounders and multiplicity (all p ≤ 0.011).ConclusionsMeal timing seems unrelated to body composition in young adults. However, a longer daily eating window and a shorter time from midsleep point to first food intake (i.e., earlier first food intake in a 24 h cycle) are associated with better cardiometabolic health in young men.Clinical trial registrationNCT02365129 (https://www.clinicaltrials.gov/ct2/show/NCT02365129?term=ACTIBATE&draw=2&rank=1).

Exploratory Study on the Associations between Lifetime Post-Traumatic Stress Spectrum, Sleep, and Circadian Rhythm Parameters in Patients with Bipolar Disorder.

The present study aimed at exploring whether lifetime post-traumatic stress spectrum symptoms are associated with chronotype in patients with bipolar disorder (BD). Moreover, we explored whether the chronotype can moderate the potential associations between lifetime post-traumatic stress spectrum symptoms and rest-activity circadian and sleep-related parameters. A total of 74 BD patients were administered the Trauma and Loss Spectrum Self-Report (TALS-SR) lifetime version for lifetime post-traumatic stress spectrum symptoms, the Pittsburgh Sleep Quality Index (PSQI) for self-reported sleep quality, and the Reduced Morningness-Eveningness Questionnaire (rMEQ) to discriminate evening chronotypes (ETs), neither chronotype (NT), and morning chronotype (MT). Actigraphic monitoring was used to objectively evaluate sleep and circadian parameters. Patients classified as ET reported significantly higher scores in the re-experiencing domain, as well as poorer sleep quality, lower sleep efficiency, increased wake after sleep onset, and delayed mid-sleep point compared with both NT and MT (p-value ≤ 0.05). Moreover, ET presented significantly higher scores in the TALS-SR maladaptive coping domain than NT and lower relative amplitude than MT (p-value ≤ 0.05). Moreover, higher TALS-SR total symptomatic domains scores were significantly correlated with poor self-reported sleep quality. Regression analyses showed that the PSQI score maintained the association with the TALS total symptomatic domains scores after adjusting for potentially confounding factors (age and sex) and that no interaction effect was observed between the chronotype and the PSQI. Conclusions: This exploratory study suggests that patients with BD classified as ET showed significantly higher lifetime post-traumatic stress spectrum symptoms and more disrupted sleep and circadian rhythmicity with respect to other chronotypes. Moreover, poorer self-reported sleep quality was significantly associated with lifetime post-traumatic stress spectrum symptoms. Further studies are required to confirm our results and to evaluate whether targeting sleep disturbances and eveningness can mitigate post-traumatic stress symptoms in BD.

The associations of chronotype and social jetlag with prosocial behavior problems among Chinese adolescents

ABSTRACT Potential relevance between the circadian rhythm and behavioral health has got raising attention in recent years. This study aimed to examine chronotype, social jetlag and their associations with prosocial behavior problems among Chinese adolescents. A total of 4,666 middle school students aged 12–18 years were enrolled in study. Sleep characteristics were collected by the modified Chinese version of Adolescent Sleep Hygiene Scale (M-ASHS); MSFsc and mid-sleep point were calculated to determine chronotypes and social jetlag. Prosocial behavior problems were assessed by the Strength and Difficult Questionnaire (SDQ). Multivariate logistic regression was applied to analyze the relationships between chronotype and social jetlag with prosocial behavior problems. Evening chronotype was associated with higher risk of prosocial behavior problems, whether among male (OR = 1.82, 95%CI:1.27–2.61, P = .001) or female adolescents (OR = 1.83, 95%CI:1.15–2.91, P = .011). Female adolescents with social jetlag of 1–2 hours had 1.60 times the risk of prosocial behavior problems than their peers whose social jetlag was <1 h (P = .028); social jetlag ≥ 2 h was positively associated with prosocial behavior problems in both male and female adolescents (OR = 1.79 and 2.45, respectively, both P < .05). Further, the combination of intermediate chronotype and social jetlag ≥ 2 h was correlated with prosocial behavior problems only in female adolescents (OR = 3.24, 95%CI = 1.40–9.21, P = .004). Evening chronotype and higher social jetlag were risk factors for prosocial behavior problems in adolescents, especially for the female. For the promotion of prosocial behavior in adolescents, the importance of circadian rhythm should be addressed.

Changes in sleep patterns of college students in Israel during COVID-19 lockdown, a sleep diaries study

To prevent and reduce the spread of COVID-19, governments around the world apply social restrictions and lockdowns. Such lockdowns significantly alter daily routine and habits. A growing body of research indicates that lockdowns affect sleep and circadian rhythms. The current study further explores this effect using sleep logs for a relatively long duration including lockdown and post-lockdown periods in Israel. For two consecutive months, both during lockdown and during post-lockdown periods, from March 13th, 2020 to May 12th, 2020, Israeli students were asked to fill out daily sleep logs in which they report their sleep and wake times. The participants were also asked to fill out the Morningness–Eveningness Questionnaire (MEQ) in the beginning of the study. Data show increase in sleep duration and a delayed midsleep point during lockdown, compared to post-lockdown periods, both on workdays and on weekends. An interaction between chronotype and lockdown was also observed; morning types sleep more both during lockdown and during post-lockdown periods. Interestingly, the midsleep point of late chronotypes is later during both workdays and weekends even during lockdown when social constrains on sleep time are in part removed. Overall, the current results based on detailed and relatively long-term sleep logs analysis confirm previous work using limited measures, such as one-time questionnaires. A lockdown period affects sleep–wake behavior: during lockdown people sleep duration is increased and their sleep onset is delayed. Nevertheless, the circadian preference of individuals is conserved across conditions.

144 Temporal and Bidirectional Associations between Objectively Measured Physical Activity and Sleep in Preschoolers

Abstract Introduction Physical activity (PA) and sleep contribute to overall health in early childhood. To explore the interactive relationships of these behaviors in older children and adults, previous studies have examined temporal between- and within-person associations through micro-longitudinal designs. However, such analyses have not been conducted in early childhood, when behaviors are guided by adult caregivers. The purpose of this analysis was to examine temporal and bidirectional associations between SED, PA, and sleep in preschool children. Methods Wake (activity counts/min and percent time in SED, light PA [LPA], and moderate-to-vigorous PA [MVPA]) and overnight sleep (sleep duration, sleep efficiency [SE], mid-sleep point [MSP]) were assessed via wrist-based actigraphy (mean = 10.4 days and 9.8 nights) and recorded as repeated (daily) measures. Multilevel models with lagged effects and AR(1) error covariance structure were used to examine the temporal associations between wake and sleep measures and adjusted for age, sex, socioeconomic status, and nap frequency. Results With PA measures as predictors, between-person associations were positive between activity counts and SE (p=0.004), SED and SE (p=0.004), LPA and sleep duration (p=0.005), and negative between LPA and MSP (p=0.039) and MVPA and SE (p=0.003). Within-person associations were positive between activity counts and sleep duration (p=0.010), activity counts and SE (p=0.018), MVPA and sleep duration (p=0.003), MVPA and SE (p=0.004), and negative between SED and SE (p=0.034) and LPA and sleep duration (p=0.045). With sleep measures as predictors, associations were positive between sleep duration and LPA (p&amp;lt;0.001) and SE and SED (p=0.008), and negative between MSP and LPA (p=0.009), SE and activity counts (p=0.001), and SE and MVPA (p=0.003). Within-person associations were positive between SE and activity counts (p=0.001) and SE and MVPA (p=0.001), and negative between sleep duration and LPA (p=0.001) and SE and SED (p=0.012). Conclusion Generally, days with higher levels of activity or sleep were not associated with greater subsequent sleep or PA. Conversely, when participants obtained greater PA or sleep compared to their individual average, some beneficial associations were evident. These findings demonstrate some evidence of temporal associations between PA and sleep, although the bidirectional nature was not conclusive. Support (if any) NIH R01 HL111695

Psychometric properties of the Morningness/Eveningness scale for children among Uruguayan adolescents: the role of school start times

ABSTRACT Morningness/Eveningness (M/E) is an attribute related to adolescent mental and physical health. The Morningness/Eveningness Scale for Children (MESC) is a widely used instrument for measuring M/E in adolescents. In this study, an Spanish translation of the MESC was adapted to the Río de la Plata population. A psychometric study was carried out in a sample of 368 Uruguayan adolescents (63.6% females), between 15 and 18 years old, who attended to either a morning (7:30 AM to 11:30 AM) or an afternoon school shift (11:30 AM to 3:30 PM). The scale showed good reliability (Cronbach’s alpha = 0.74), high temporal stability (r = 0.86, p < 0.001), good concurrent validity with mid-sleep point (r = −0.42, p < 0.001), and a two-factor solution. No difference in scores was observed between sexes or age groups. However, scores were different between school shifts, which proved to be a useful tool to study social influences on the circadian preferences. This study shows that MESC is a reliable and valid instrument for M/E assessment in adolescents, but social pressures should be considered when employing this score.

SLEEP DURATION AND TIMING ARE NOT ASSOCIATED WITH ANTIMULLERIAN HORMONE LEVELS

Many women who consider future family building seek advice regarding modifiable behaviors and reproductive health. To determine if sleep duration and timing are associated with AMH levels in a reproductive aged, Midwestern cohort of women. Cross sectional study. 200 women aged 18-44 years with regular menstrual cycles were enrolled into the LORE study, a cross-sectional cohort study designed to investigate associations between lifestyle factors and ovarian reserve. Women who were currently pregnant or who had history of major chronic illness, infertility or ovarian surgery were excluded. Fasting blood was drawn and stored at -80 degrees for batched analysis. Samples were run on the Roche Elecsys analyzer for AMH levels. Participants also completed a survey that included questions regarding typical bedtime and wake time on work and non-work days. Sleep measures included duration of sleep, midsleep point (defined as the midpoint time between bedtime and wake time, also known as chronotype), and social jetlag (the difference in midsleep point on workdays and non-work days of >1 hour). Standard bivariate statistics were run to determine associations between sleep duration, timing of sleep and AMH levels. SPSS v.25 was used for analysis. Participants had an average age of 30.9 ± 6.7 years and an average body mass index of 28.3 ±7.1. The majority of the participants were white (n=136, 68%); thirty percent were black (n=60). The average AMH level was 2.9 ±2.0 ng/mL. Average duration of sleep was 7.2 hours (Range 4.0 to 11.0 hours). Average mid sleep point on work nights was 2:51 AM and on non-work nights was 3:54 AM. Average social jet lag was 1:31 hours (range 0 to 14:30 hours). None of these measures were associated with AMH. This data suggests that for healthy, reproductive aged women in the Midwest, modifying sleep duration and timing is unlikely to improve or adversely affect AMH.

Validation of the Portuguese Variant of the Munich Chronotype Questionnaire (MCTQPT).

IntroductionDifferences in the manner circadian clocks entrain to the 24-h day are expressions of different chronotypes that can range from extreme early to extreme late, from proverbial larks to owls. The Morningness Eveningness Questionnaire (MEQ) was one of the first to assess daily preference based on subjective self-assessment – a psychological construct. The later developed Munich Chronotype Questionnaire (MCTQ) uses instead the actual sleep timing to assess chronotype. It calculates the mid-sleep point, halfway between onset and offset on work-free days (MSF), which is then corrected for potential oversleep on free days compensating for sleep debt accumulated over the workweek (MSFsc). MSFsc is expressed in local time and is thought to be a proxy for “phase of entrainment” of the circadian clock. The MCTQ-derived chronotype is therefore a biological construct. In the present report, we validate the Portuguese variant (MCTQPT) of the MCTQ. Portugal is of particular interest, since it is thought to consist of especially late chronotypes.MethodsWe have used three methods to assess the timing of daily behavior, namely, the chronotype (MCTQ), the daily preference (rMEQ), and a simple self-assessment (time-of-day type). A total of 80 healthy adults living in Portugal, with age and sex distributed according to the Portuguese population, were recruited. We analyzed 4 weeks of continuous records of actimetry data to validate the MCTQPT and used the rMEQ to compare between a biological chronotype (sleep timing) and a psychological chronotype (daily preference). MCTQ variables were analyzed by descriptive statistics; correspondence between measurements was done by Spearman correlations or cross-tabulation; in a subset of 41 individuals, test–retest reliability was assessed.ResultsMCTQ-derived variables (MSF, MSW, MSFsc) correlated highly with their counterparts calculated from actimetry (MSW: rho = 0.697; MSF: rho = 0.747; MSFsc: rho = 0.646; all p < 0.001). The MCTQ assessment of the chronotype showed good test–retest reliability (rho = 0.905; p < 0.001). The rMEQ score correlates with MSFsc (rho = −0.695; p < 0.001), and the agreement for the self-assessment with the MSFsc was fair (kw = 0.386; p < 0.001).ConclusionThe Portuguese variant of the MCTQ revealed to be a reliable questionnaire to assess the chronotype for the Portuguese adult population, as previously reported for other countries.

A daily diary study of sleep chronotype among Mexican-origin adolescents and parents: Implications for adolescent behavioral health.

The current study used daily assessments of sleep to examine stability and change in sleep chronotype in adolescents and their parents. The study assessed adolescent sleep chronotype according to age, gender, and parent chronotype, and evaluated its associations with emotional and behavioral problems in youth. Participants included of 417 Mexican American adolescents (Mage = 16.0 years, Range = 13.9-20.0) and 403 caregivers, who reported bed and wake times daily for 2 consecutive weeks at two time points spaced 1 year apart. In addition, adolescents completed established self-report questionnaires of emotional and behavioral problems. Chronotype was computed as the midsleep point from bed to wake time on free days, correcting for sleep debt accumulated across scheduled days. Multilevel modeling showed a curvilinear association between adolescent age and chronotype, with a peak eveningness observed between ages 16 to 17. Adolescent and parent chronotypes were contemporaneously correlated, but each was only moderately stable over the 1-year period. Later adolescent chronotype was contemporaneously associated with more substance use in all adolescents. Individual development and the family context shape sleep chronotype in adolescents and parents. Sleep chronotype is implicated in adolescent behavioral health.

Relationships between circadian measures, depression, and response to antidepressant treatment: A preliminary investigation

Few studies have examined relationships between circadian rhythms and unipolar major depressive disorder. Further, no study to date has examined circadian markers as predictors of response to depression treatment. In the present study, we examined associations between circadian timing and its alignment with sleep and depression severity in 30 adults with major depressive disorder who completed a randomized controlled trial of two weeks of time in bed (TIB) restriction administered adjunctive to fluoxetine, with a focus on sex differences. Thirty adults with major depressive disorder received 8 weeks of fluoxetine 20–40 mgs and were randomized to 8h TIB or 6h TIB for the first 2 weeks. Participants in the 6h TIB condition were further randomized to a delayed bedtime or advanced risetime group. Circadian measures included dim light melatonin onset (DLMO) and the difference between DLMO and midsleep point (i.e., phase angle difference). Depression was assessed using the Hamilton Rating Scale for Depression. For females, a phase delay after 2 weeks of fluoxetine and the experimental TIB manipulation was associated with a poorer response to fluoxetine, and depression severity was negatively correlated with phase angle difference, whereas males showed a positive correlation between depression severity and phase angle difference.

Extreme late chronotypes and social jetlag challenged by Antarctic conditions in a population of university students from Uruguay

In humans, a person’s chronotype depends on environmental cues and on individual characteristics, with late chronotypes prevailing in youth. Social jetlag (SJL), the misalignment between an individual׳s biological clock and social time, is higher in late chronotypes. Strong SJL is expected in Uruguayan university students with morning class schedules and very late entertainment activities. Sleep disorders have been reported in Antarctic inhabitants, that might be a response to the extreme environment or to the strictness of Antarctic life. We evaluated, for the first time in Uruguay, the chronotypes and SJL of 17 undergraduate students of the First Uruguayan Summer School on Antarctic Research, using Munich Chronotype Questionnaire (MCTQ) and sleep logs (SL) recorded during 3 phases: pre-Antarctic, Antarctic, and post-Antarctic. The midsleep point of free days corrected for sleep debt on work days (MSFsc,) was used as proxy of individuals’ chronotype, whose values (around 6a.m.) are the latest ever reported. We found a SJL of around 2h in average, which correlated positively with MSFsc, confirming that late chronotypes generate a higher sleep debt during weekdays. Midsleep point and sleep duration significantly decreased between pre-Antarctic and Antarctic phases, and sleep duration rebounded to significant higher values in the post-Antarctic phase. Waking time, but not sleep onset time, significantly varied among phases. This evidence suggests that sleep schedules more likely depended on the social agenda than on the environmental light–dark shifts. High motivation of students towards Antarctic activities likely induced a subjective perception of welfare non-dependent on sleep duration.

Insomnia, Nightmares, and Chronotype as Markers of Risk for Severe Mental Illness: Results from a Student Population.

To group participants according to markers of risk for severe mental illness based on subsyndromal symptoms reported in early adulthood and evaluate attributes of sleep across these risk categories. An online survey of sleep and psychiatric symptomatology (The Oxford Sleep Survey) was administered to students at one United Kingdom university. 1403 students (undergraduate and postgraduate) completed the survey. The median age was 21 (interquartile range = 20-23) and 55.60% were female. The cross-sectional data were used to cluster participants based on dimensional measures of psychiatric symptoms (hallucinations, paranoia, depression, anxiety, and (hypo)mania). High, medium, and low symptom groups were compared across sleep parameters: insomnia symptoms, nightmares, chronotype, and social jet lag. Insomnia symptoms, nightmares frequency, and nightmare-related distress increased in a dose-response manner with higher reported subsyndromal psychiatric symptoms (low, medium, and high). The high-risk group exhibited a later chronotype (mid sleep point for free days) than the medium- or low-risk group. The majority of participants (71.7%) in the high-risk group screened positive for insomnia and the median nightmare frequency was two per 14 days (moderately severe pathology). Insomnia, nightmares, and circadian phase delay are associated with increased subsyndromal psychiatric symptoms in young people. Each is a treatable sleep disorder and might be a target for early intervention to modify the subsequent progression of psychiatric disorder.

Turkish Validation and Adaptation of Children ’s Chronotype Questionnaire (CCTQ)

Chronotype refers to the time of the day that a person's physical and cognitive functions are active. Simply this is a circadian phase preference of a person. While some of the people are morning active (so called larks) others are more active at nights (The owls). The study of circadian rhythms, known as chronobiology, is all about the metabolic and psychiatric differences between people who have different chronotypes. A few tests are used to determine chronotypes. The CCTQ (Children's Chronotype Questionnaire) is a parent-report, 27-item mixed format questionnaire measuring chronotype of children in multiple domains : the midsleep point on free days (MSF), a morningness/eveningness scale(M/E) score, and a five-point chronotype (CT) score. The aim of this study is adapting Children's Chronotype Questionnaire (CCTQ) into Turkish language and validating the instrument in Turkish population. 101 children aged nine through eighteen constitude the sample of the study. The sample was composed of clinical (n=51) and community groups (n=50). CCTQ and Morningness Eveningness Scale for Children (MESC) questionnaires were applied to children and parents, then the CCTQ and MESC scores were compared to examine the validity of CCTQ. The internal consistency and external validity of the Turkish CCTQ was sufficient to compare MESC-Turkish. As a result of this research carried out in accordance with methodological research principles, correlation between the M/E scores of CCTQ and MESC was significant. The Turkish version of CCTQ has been found to be valid and reliable in Turkish children.

Social jetlag negatively correlates with academic performance in undergraduates

Discrepancies between sleep timing on workdays and weekends, also known as social jetlag (SJL), affect the majority of the population and have been found to be associated with increased health risk and health-impairing behaviors. In this study, we explored the relationship between SJL and academic performance in a sample of undergraduates of the Semmelweis University. We assessed SJL and other sleep-related parameters with the Munich ChronoType Questionnaire (MCTQ) (n = 753). Academic performance was measured by the average grade based on weekly test results as well as scores acquired on the final test (n = 247). The average mid-sleep point on free days in the Hungarian sample fits well the regression line plotted for longitudes within the Central European Time Zone and chronotypes, confirming that sunlight has a major impact on chronotype. Multivariate analysis showed negative effect of SJL on the weekly average grade (p = 0.028, n = 247) during the lecture term with its highly regular teaching schedules, while this association disappeared in the exam period (p = 0.871, n = 247) when students had no scheduled obligations (lower SJL). We also analyzed the relationship between the time of the weekly tests and academic performance and found that students with later sleep times on free days achieved worse in the morning (p = 0.017, n = 129), while the inverse tendency was observed for the afternoon test-takers (p = 0.10, n = 118). We did not find significant association between academic performance and sleep duration or sleep debt on work days. Our data suggest that circadian misalignment can have a significant negative effect on academic performance. One possible reason for this misalignment is socially enforced sleep times.

Diurnal type in children: Preliminary results about the European Portuguese version of the CCTQ

Few tools exist to measure morningness–eveningness in young children. Recently, Werner, LeBourgeois, Geiger and Genni published the Children Chronotype Questionnaire (CCTQ), a parental 27 item questionnaire designed to extract three chronotype measures, in 4–11 years old children. The aim of the present study was to develop an European Portuguese version [PT] of the CCTQ and to examine its psychometric properties. A permission request to develop a Portuguese version was sent to the CCTQ authors. A first translation draft was generated; next it was examined by experts; the resulting version was after that tested using “thinking aloud” procedures, and then an experimental CCTQ [PT] version was defined. This version was completed by a sample of parents/tutors of 397 children (47.1% boys), 4−11 yrs-old. Based on their answers, three chronotype measures were computed: the morningness/eveningness scale score (M/E); the midsleep point on free days (MSF); the five point chronotype score (CT). As to internal consistency, Chronbach alpha for the M/E scale was 0.71. Corrected item-total correlations ranged from .28 to .55, with an average of .39. With regard to the chronotype measures, scores on the M/E scale showed a gaussian distribution with a mean of 28.2 (SD = 6.0, Min = 15 and Max = 44); for MSF a mean of 3:47 (SD = 44 min) was obtained; and at the CT measure a median of 2 was found. Correlation coefficients between the chronotype measures revealed moderate to strong associations (from rs = .34 to r = .54). These preliminary results found in our sample for the Portuguese CCTQ were similar to the ones obtained on the original CCTQ, for the M/E scale. However, our children showed later schedules, as expressed by MSF. This first Portuguese study, together with the authors’ comments on the back translation, highlighted the strengths of our experimental version, but also some aspects to refine, which led us to define the final Portuguese version of the CCTQ. A study in a larger national sample is now needed. We are grateful to Dr. Werner, Professor Jenni, and remaining CCTQ authors for their permission to develop the Portuguese version. Thanks are also due to the Dep. of Education (Univ. Aveiro) for the support regarding the printed materials used in data collection. The present work is currently supported by Research Project PTDC/PSI-EDD/120003/2010 funded by FCT/COMPETE/QREN.

Sleep timing is more important than sleep length or quality for medical school performance

Overwhelming evidence supports the importance of sleep for memory consolidation. Medical students are often deprived of sufficient sleep due to large amounts of clinical duties and university load, we therefore investigated how study and sleep habits influence university performance. We performed a questionnaire-based study with 31 medical students of the University of Munich (second and third clinical semesters; surgery and internal medicine). The students kept a diary (in 30-min bins) on their daily schedules (times when they studied by themselves, attended classes, slept, worked on their thesis, or worked to earn money). The project design involved three 2-wk periods (A: during the semester; B: directly before the exam period—pre-exam; C: during the subsequent semester break). Besides the diaries, students completed once questionnaires about their sleep quality (Pittsburgh Sleep Quality Index [PSQI]), their chronotype (Munich Chronotype Questionnaire [MCTQ]), and their academic history (previous grades, including the previously achieved preclinical board exam [PBE]). Analysis revealed significant correlations between the actual sleep behavior during the semester (MSdiary; mid-sleep point averaged from the sleep diaries) during the pre-exam period and the achieved grade (p = 0.002) as well as between the grades of the currently taken exam and the PBE (p = 0.002). A regression analysis with MSdiary pre-exam and PBE as predictors in a model explained 42.7% of the variance of the exam grade (effect size 0.745). Interestingly, MSdiary—especially during the pre-exam period—was the strongest predictor for the currently achieved grade, along with the preclinical board exam as a covariate, whereas the chronotype did not significantly influence the exam grade.