Late Chronotype Research Articles

Sleep as a biological rhythm: clinical aspects

Insomnia is a widespread disorder affecting not only sleep quantity and quality, but also daytime well-being and performance, as well as having a negative impact on physical and mental health. Many people have problems falling asleep and maintaining sleep that do not reach the clinical criteria of insomnia. For all the prevalence of such sleep disorders, specialists often overlook a fundamentally important factor that affects sleep and wakefulness cycle, ease of falling asleep and daytime performance. These are circadian rhythms of the body under the control of the biological clock.This review highlights the specifics of the human biological clock and its relationship to insomnia and complaints of poor sleep. The phenomenon of the human chronotype as a set of individual preferences in sleep-wake rhythm is considered. Late chronotype, tat tends to wake up late and be active in the evening turns out to be the most vulnerable to the appearance of complaints of poor sleep and development of insomnia. This result is typical for different age groups. The reason for problems sleep for the late chronotype is the need to adjust to social demands and to fall asleep and wake up too early relative to the phase of one’s own circadian rhythm.Circadian rhythms may contribute to the formation and maintenance of insomnia. Both chronic and acute insomnia may have a chronobiological component that is not always considered. Late chronotype may be a factor further exacerbating the course of insomnia. The regularity of circadian rhythms may also be impaired in insomnia.The importance of the biological clock in the regulation of sleep and wakefulness also explains the successful approach to insomnia treatment with melatonin, which plays an important signaling role in the circadian regulation of the body.

Evidence for Co-Evolution of Masking With Circadian Phase in Drosophila Melanogaster.

Heritable variation in the timing of rhythmic events with respect to daily time cues gives rise to chronotypes. Despite its importance, the mechanisms (clock or non-clock) regulating chronotypes remain elusive. Using artificial laboratory selection for divergent phasing of emergence of adults from pupae, our group has derived populations of Drosophila melanogaster which are early and late chronotypes for eclosion rhythm. Several circadian rhythm characteristics of these populations have since been described. We hypothesized that our selection protocol has inadvertently resulted in selection for masking, a non-clock phenomenon, in the early chronotype due to the placement of our selection window (which includes the lights-ON transition). We designed experiments to discriminate between enhanced masking to light versus circadian clock mediated changes in determining enhanced emergence in the morning window in our early chronotypes. Using a series of phase-shift protocols, LD-DD transition, and T-cycle experiments, we find that our early chronotypes have evolved positive masking, and their apparent entrained phases are largely contributed by masking. Through skeleton T-cycle experiments, we find that in addition to the evolution of greater masking, our early chronotypes have also evolved advanced phase of entrainment. Furthermore, our study systematically outlines experimental approaches to examine relative contributions of clock versus non-clock control of an entrained behavior. Although it has previously been suggested that masking may confer an adaptive advantage to organisms, here we provide experimental evidence for the evolution of masking as a means of phasing that can complement clock control of an entrained behavior.

Daily activity rhythms, chronotypes, and risk-taking behavior in the signal crayfish.

Consistent inter-individual differences in daily activity rhythms (i.e., chronotypes) can have ecological consequences in determining access to food resources and avoidance of predators. The most common measure to characterize chronotypes in animals as well as humans is the onset of activity (i.e., early or late chronotypes). However, daily activity rhythms may also differ in the relative amount of activity displayed at particular time periods. Moreover, chronotypes may also be linked to other consistent inter-individual differences in behavior (i.e., personality), such as the propensity to take risks. Here, we used the signal crayfish Pacifastacus leniusculus to test the presence of chronotypes and risk-taking personality traits and a potential behavioral syndrome between these traits. We first exposed crayfish to 5 days of light–darkness to measure daily activity rhythms and then we applied a visual predator-simulating stimulus in 2 different contexts (neutral and food). Our results showed consistent (i.e., across 5 days) inter-individual differences in the relative nocturnal activity displayed in the early and middle, but not in the late part of darkness hours. Moreover, while crayfish displayed inter-individual differences in risk-taking behavior, these were not found to be consistent across 2 contexts. Therefore, we were not able to formally test a behavioral syndrome between these 2 traits. In conclusion, our study provides the first evidence of chronotypes in the relative amount of activity displayed at particular time periods. This could be a valuable information for applied ecological aspects related to the signal crayfish, which is a major invasive species of freshwater ecosystems.

Mental rotation performance and circadian chronotype in university students: a preliminary study

ABSTRACT The present study aimed to explore the influence of the chronotype on mental rotation performance in university students. Using the Morningness-Eveningness Questionnaire (MEQ), 24 healthy volunteers were categorized as either early chronotype (ECT) or late chronotype (LCT). Participants completed a chronometric mental rotation task with three-dimensional stimuli at different times of day (8 AM and 8 PM). ECT participants showed a shorter reaction time in the morning trial than in the evening (p = 0.003), whereas LCT participants showed a shorter reaction time (p = 0.001) and increased accuracy (p = 0.031) in the evening compared to the morning session. Additionally, the MEQ score was positively correlated with the difference in reaction time between morning and evening trials (r = −0.589, p = 0.002). Two-way analysis of variance revealed an interaction between time and chronotype for the parameter reaction time in the evening trials (F(1, 22) = 28.27, p < 0.001). LCT participants showed higher speed and increased accuracy during their optimal time compared to ECT participants. This study explored diurnal alterations of visual-spatial abilities assessed as mental rotation performance, and the possible implications for certain life skills such as sports, car driving, and manual labor are discussed.

Sleep and chronotype in relation to work-related stress and negative affect: The moderating role of a flexible start of work

Abstract Objectives The present study investigated the relationships between sleep (sleep duration and need for additional sleep time in the morning), chronotype, work-related stress, and negative affect in daytime workers. Furthermore, it was examined whether a flexible start of work moderates these relationships. Methods A cross-sectional online study was conducted. Participants were 438 (247 female) daytime workers between 18 and 73 years (mean = 37.68, standard deviation = 12.39). The questionnaire included the “sleep duration” subscale of the Pittsburgh Sleep Quality Index (PSQI), the Morningness–Eveningness Questionnaire (MEQ), two subscales of the Trier Inventory for the Assessment of Chronic Stress (TICS), the negative affect scale of the Positive and Negative Affect Schedule (PANAS), questions regarding how many minutes participants would like to sleep longer in the morning, and how flexible their start of work is. Results Short sleep duration and a greater need for additional sleep in the morning were significantly associated with late chronotype. Shorter sleep duration, a greater need for additional sleep, and a late chronotype were associated with higher work-related stress and negative affect. A flexible start of work moderated these relationships: People with longer sleep duration, less need for additional sleep time, and an early chronotype showed lower stress and negative affect levels when having a flexible start of work. A flexible start of work showed no or negative effects on workers with shorter sleep duration, a greater need for additional sleep time, or a late chronotype. Conclusions The effect of a flexible start of work for daytime worker’s well-being depends on a person’s individual sleep timing and chronotype.

Do sleep quality and caffeine consumption mediate the relationship between late chronotype and body mass index?

To determine the role of sleep quality and caffeinated beverage consumption in the effect of late chronotype on body mass index (BMI). The study consisted of a total of 661 healthy university students with a mean age of 21.4 ± 1.38 years. Within the scope of the study, The Morningness-Eveningness Questionnaire (MEQ) was used to determine the chronotypes of individuals, the Pittsburgh Sleep Quality Index (PSQI) was used to determine sleep quality, and a 24 h physical activity record was taken to determine physical activity levels. The caffeine intake of the individuals was determined using a food frequency questionnaire for the intake of caffeinated food and beverages. The role of mediators in the effect of late chronotype on BMI was evaluated via multiple mediation analysis. In this study, evening-type individuals had higher daily caffeine intake, worse sleep quality (P < 0.001), and higher BMI (P < 0.05). When the effect of mediators was taken into account, the negative relationship between the chronotype score and BMI was maintained (β = -0.109, 95% CI (-0.194, -0.021), P < 0.05). Decreased sleep quality had a mediated effect in this relationship [β = -0.208, 95% CI (-0.275, -0.119)], and caffeinated beverage consumption was found to have no mediator function (β = 0.040 95% CI (-0.050, 0.108), P > 0.05). To conclude, eveningness chronotype had an effect on higher levels of caffeinated beverage consumption, lower sleep quality, and increased BMI. Chronotype, sleep quality, and caffeinated beverage consumption should be taken into account in studies examining the relationship between circadian rhythm and obesity.

Social Jetlag and Prostate Cancer Incidence in Alberta's Tomorrow Project: A Prospective Cohort Study.

Simple SummaryDue to social obligations (e.g., school, work), people shift their sleep and activity time regardless of their sleep-wake preference. To compensate for the lack of sleep accumulated over the workdays, people tend to oversleep on a work-free day. This difference in sleep timing between workdays and free days resembles traveling across different time zones, which causes jetlag (a mild form of circadian disruption). Thus, it is named social jetlag. Social jetlag has been linked with obesity, metabolic disorders, and cardiovascular risk in previous research. This study assessed social jetlag in 7455 cancer-free men in Alberta’s Tomorrow Project and followed them for on average 9.6 years, 250 men were diagnosed with prostate cancer. The study found that the more social jetlag men experienced, the greater their prostate cancer risk was. This finding warrants future research to better understand the complex behavioral and biological pathways between social jetlag and prostate cancer risk.We investigated the association of social jetlag (misalignment between the internal clock and socially required timing of activities) and prostate cancer incidence in a prospective cohort in Alberta, Canada. Data were collected from 7455 cancer-free men aged 35–69 years enrolled in Alberta’s Tomorrow Project (ATP) from 2001–2007. In the 2008 survey, participants reported usual bed- and wake-times on weekdays and weekend days. Social jetlag was defined as the absolute difference in waking time between weekday and weekend days, and was categorized into three groups: 0–<1 h (from 0 to anything smaller than 1), 1–<2 h (from 1 to anything smaller than 2), and 2+ h. ATP facilitated data linkage with the Alberta Cancer Registry in June 2018 to determine incident prostate cancer cases (n = 250). Hazard ratios (HR) were estimated using Cox proportional hazards regressions, adjusting for a range of covariates. Median follow-up was 9.57 years, yielding 68,499 person-years. Baseline presence of social jetlag of 1–<2 h (HR = 1.52, 95% CI: 1.10 to 2.01), and 2+ hours (HR = 1.69, 95% CI: 1.15 to 2.46) were associated with increased prostate cancer risk vs. those reporting no social jetlag (p for trend = 0.004). These associations remained after adjusting for sleep duration (p for trend = 0.006). With respect to chronotype, the association between social jetlag and prostate cancer risk remained significant in men with early chronotypes (p for trend = 0.003) but attenuated to null in men with intermediate (p for trend = 0.150) or late chronotype (p for trend = 0.381). Our findings suggest that greater than one hour of habitual social jetlag is associated with an increased risk of prostate cancer. Longitudinal studies with repeated measures of social jetlag and large samples with sufficient advanced prostate cancer cases are needed to confirm these findings.

Time of Day Matters: An Exploratory Assessment of Chronotype in a Forensic Psychiatric Hospital.

A growing body of evidence links the late chronotype to mental illness, aggression, and aversive personality traits. However, much of what we know about these associations is based on healthy cohorts, and it is unclear how individuals with high levels of aggression, including forensic psychiatric populations, but not offenders, are affected. The present study aimed to measure chronotype in a forensic psychiatric inpatient population, evaluate the impact of diagnosis, and identify any interactive relationships between chronotype, diagnosis, aggression, and dark triad traits. Subjects completed the reduced Morningness–Eveningness Questionnaire (rMEQ), Munich ChronoType Questionnaire (MCTQ), Pittsburgh Sleep Quality Index (PSQI), Buss Perry Aggression Questionnaire–Short Form (BPAQ-SF), and Short Dark Triad Questionnaire (SD3). We sampled 55 forensic psychiatric patients (52 males) between the ages of 23 and 73 years (mean ± SD: 39.6 ± 14.3 years). Among the patients sampled, 25% were evening types and 36% were morning types. Eveningness was greater in patients with a personality disorder; however, no chronotype differences were found for psychosis patients. Patients without psychosis had a positive association between anger and eveningness, as well as between hostility and eveningness. For subjects with a substance use disorder, morningness was positively associated with narcissism. Conversely, an association between eveningness and greater narcissism was identified in patients who did not have a substance use disorder. These findings suggest that, compared to the general population, evening types are more prevalent in forensic psychiatric populations, with the strongest preference among patients diagnosed with a personality disorder. No differences in chronotype were identified for psychosis patients, which may be related to anti-psychotic medication dosing. Given the sex distribution of the sample, these findings may be more relevant to male populations.

Sex differences in the association between chronotype and risk of depression

Information on sex differences in the association between chronotype and depression is scarce. We aimed to investigate these differences using data from the Korea National Health and Nutrition Examination Survey in 2016. Chronotypes were categorised based on mid-sleep time on free days corrected by sleep debt accumulated on workdays (MSFsc): early type, < mean MSFsc − 1 standard deviation (SD); intermediate type, between mean MSFsc − 1 SD and MSFsc + 1 SD; and late type, > mean MSFsc + 1 SD. A Patient Health Questionnaire-9 score of ≥ 10 indicated depression. Among 5550 non-shift working adults aged 19–80 years, the prevalence rates of depression in the early, intermediate, and late chronotype groups were 7.4%, 4.5%, and 9.3%, respectively. Women with late chronotype (odds ratio [OR] = 2.9, 95% confidence interval [CI] = 1.8–4.7) showed a higher risk of depression than women with intermediate chronotype after adjusting for covariates. Women with early chronotype did not show a significant difference in depression risk (OR = 1.3, 95% CI = 0.9–2.0). In conclusion, late chronotype is associated with an increased risk of depression in women but not in men. Early chronotype is not associated with depression in women or men.

Creativity and the Alignment between Chronotype and Time of Day

We examine the influence of chronobiological processes on creativity, specifically the influ-ence of a person’s chronotype. Chronotype refers to the setting of a person’s biological clock that gives rise to a distinctive pattern of sleep habits and preferred diurnal activity. We propose a syn-chrony effect and predict that people display peaks in creativity during a work day when the exter-nal clock is aligned with their internal, biological clock. According to our model, positive mood and creative self-efficacy act as affective and cognitive mechanisms of this synchrony effect. We pre-sent a one-day experience sampling study with 339 employees to test our theorizing. In support of our hypothesis, we find peaks in creativity when employees’ biological clocks and the time of day were ‘in sync’. Early chronotypes showed peaks in creativity in the morning, while late chrono-types showed peaks in creativity in the late afternoon. The study further demonstrates that positive mood and creative self-efficacy are parallel mediators of the synchrony effect. We discuss the theo-retical and practical implications of these findings against the background of an embodied cognition perspective on creativity.

Short Sleep Duration and Extremely Delayed Chronotypes in Uruguayan Youth: The Role of School Start Times and Social Constraints.

During adolescence, biological, psychosocial, and contextual factors converge in a "perfect storm" and have been put forward to explain the delay in chronotype observed at this age and the prevalence of disrupted sleep. This study provides evidence to support that chronotype and sleep patterns (particularly sleep duration) are socially constrained and to identify novel significant social predictors. Uruguayan public school activities are arranged in up to 4 shifts, creating a natural experiment to examine the effect of school timing on questionnaire-based assessments of sleep and chronotype. In this study, 268 high school students (15-18 years old) who attended school either on morning (0730 to 1130 h) or afternoon shifts (1130 h to 1530 h) responded to an adapted School Sleep Habits Survey. Students attending afternoon shifts had later chronotypes (a 1.5-h later midpoint of sleep on free days adjusted for sleep debt) than those attending the morning shift. Besides shift, evening social activities (including dinner time) were further identified as key predictors of late chronotypes, whereas age and gender were not. Sleep on school days was overall advanced and reduced with respect to weekends, and these effects were stronger in morning-shift students. Weekend sleep duration was similar between shifts, which probably caused the prevalence of reduced sleep durations (average weekly sleep duration, SDweek <8 h) to be higher in morning-shift students (almost 80%) than in afternoon-shift ones (34%). Reduced sleep duration was significantly higher in morning-shift students. In addition, age, chronotype, and dinner time became relevant determinants of sleep deficit only in the morning-shift students. Besides the important social constraint of early school start time, this is the first study to confirm the significance of other types of social pressures on both adolescents' chronotype and sleep deficit, which can be useful as potential new targets for effective policies to protect adolescent sleep.

0414 Chronotype and Sleep Among Ovarian Cancer Survivors Participating in a Lifestyle Intervention

Abstract Introduction Chronotype is defined as an individual’s propensity to sleep at a specific time in a 24-hour cycle with late chronotype associated with poorer health outcomes including cancer. The role of chronotype on lifestyle behaviors remains relatively undefined in ovarian cancer. The Lifestyle Intervention for oVarian cancer Enhanced Survival study is testing whether 1205 women randomized to a diet and physical activity intervention for 24-months will have longer progression-free survival versus attention control. Here we determine the frequency and predictors of late versus early and mid chronotypes in disease-free ovarian cancer survivors. Methods 894 ovarian cancer survivors with baseline measures were included in analyses. Chronotypes were determined using self-reported time to bed (early- &amp;lt; 9 pm; mid- ≥ 9 pm - ≤12 am; late- &amp;gt;12 am) captured through the Pittsburgh Sleep Quality Index. Demographic, diet and physical activity data were captured with validated questionnaires and BMI measured in clinic. Descriptive statistics and logistic regression, adjusted for smoking status and race, were performed. Results 12.4% of women were late chronotype with significant differences between chronotypes observed for race, smoking history, sleep duration, and physical activity (p &amp;lt; 0.05). Late chronotype reported fewer hours of sleep per night (6.54 ± 1.51hrs) compared to mid (7.10± 1.31hrs) and early (7.74 ± 1.30hrs) chronotype. Blacks had higher odds of being late chronotype, OR 4.28 (95% CI 2.16-8.46). Late chronotype were more likely to report a history of smoking and lower recreational activity and had a higher mean BMI of 29.1± 6.0 kg/m2 compared to mid and early chronotype 27.8± 6.2 kg/m2 and 27.4± 5.4kg/m2, respectively. No significant differences were observed for sleep or diet quality, age, education or employment status. Conclusion Results of this analysis are consistent with other community-based population studies with regard to chronotype and race. Ovarian cancer is aggressive and late chronotype are more likely to have other risk factors that elevate risk of recurrence (obesity, tobacco use and inactivity. Six-month data are being analyzed by treatment arm and will provide important insights as to the role of sleep phase and lifestyle behaviors in this vulnerable population. Support NCT00719303; NCI R01CA186700-01A1

0785 Associations Between Circadian Preference And Sleep-related Thoughts: Data From The 2015 Sleep In America Poll

Abstract Introduction Evening types of sleep tend to have poorer sleep quality and sleep habits than morning types. Maladaptive beliefs or thoughts about sleep can affect one’s sleep and may differ between evening and morning types. We examined the association between the circadian preference and sleep-related thoughts in U.S adults. Methods A secondary analysis used survey data from the 2015 National Sleep Foundation’s Sleep in America Poll. Questions included normal bedtime and wake-up time for week/work days and weekend/non-work days. Circadian preference was determined by midpoint of sleep calculated as midpoint of sleep on weekends corrected for average nightly sleep duration. Participants were excluded if their sleep midpoint was from noon to midnight. Midpoint of sleep was divided into two groups using median split (“earlier” vs. “later”). Sleep-related thoughts were “worry about getting a good sleep”, “overwhelming thoughts about getting enough sleep”, “motivation to get sleep”, and “concern about serious physical consequences due to poor sleep”; responded often/always or extremely to somewhat for these items were coded as maladaptive. Logistic regression analysis controlling for socio-demographics, sleep duration, and sleep disturbance (PROMIS Scale; higher scores = greater sleep disturbance) was conducted to examine the relationships between midpoint of sleep and sleep-related thoughts. Results The sample (N = 1011) was primarily White (73.6%), male (50.9%), college educated (62.2%), married/partnered (67.6%) with a mean age of 51.65 ± 17.05 years. Mean midpoint of sleep in “earlier” type was 2:33AM and 5:29AM in “later” type. “Later” type had shorter sleep duration on weekdays and longer sleep duration on weekends than “earlier” type (p &amp;lt; .01), but average sleep duration was similar between two types. “Later” type had more “worry” and “overwhelming thoughts” (p &amp;lt; .05) about sleep. In logistic models, midpoint of sleep was significant only for “concern” (p = .02). Conclusion In this study, late chronotype was associated with increased sleep disturbances and greater variability in sleep duration. The relationship between the timing of sleep and thoughts about the impact of impaired sleep remains unclear and an area for further study with objective measures. Support

0245 Relationship of Chronotype with Sleep Duration, Daytime Sleepiness, and Sustained Attention in High School Students: A Pilot Study

Abstract Introduction People with a later chronotype typically sleep later and perform better later in the day. In an early high school schedule, students with later chronotypes earn lower average grades than those with earlier chronotypes. However, other effects of late chronotype on high school students are poorly understood. This study examined the relationship of chronotype with sleep duration, daytime sleepiness and sustained attention in high school students. Methods This study was conducted at Byram Hills High School in Armonk, NY, where classes begin at 7:45am. During three class periods, 36 participants (female n=24, n=12, 14–17 years old) completed the Morning-Eveningness Questionnaire (MEQ), Karolinska Sleepiness Scale (KSS), and Psychomotor Vigilance Test (PVT) during their class. Subjects recorded time spent on homework/extracurricular activities and bedtime/waketime from the night prior to the assessment. Results Later chronotype (lower MEQ score) was significantly associated with later bedtime, shorter sleep duration, and increased sleepiness (r=-0.82, p&amp;lt;0.001; r=0.72, p&amp;lt;0.001; and r=-0.40, p=0.016; respectively). Shorter sleep duration was significantly correlated with increased sleepiness (r=-0.34, p=0.045). Increased workload (time on homework/extracurriculars) was significantly associated with later bedtime (r=0.42, p=0.011). Chronotype, sleep duration, and sleepiness showed no significant association with PVT scores (r=-0.16, p=0.360; r=-0.10, p=0.933; r=0.09, p=0.619, respectively); however, increased workload was significantly associated with increased PVT scores (r=-0.35, p=0.041). Conclusion These results are important for the wellbeing of high school students, as they show relationships between late chronotype, short sleep, and increased sleepiness during class in an early school schedule. Further research is needed to determine the best school schedule for high school students based on individual differences in chronotype. Support We thank the Authentic Science Research program at Byram Hills High School, specifically teachers Mrs. Stephanie Greenwald, Dr. Caroline Matthew, and Mrs. Megan Salomone.

Impact of Meal Timing and Chronotype on Food Reward and Appetite Control in Young Adults.

Early meal timing and chronotype are associated with lower BMI, but their impact on appetite is poorly understood. We examined the impact of meal timing and chronotype on appetite and food reward. Forty-four adults were divided into early (EC; Morningness–Eveningness Questionnaire (MEQ) score = 55 ± 5) or late chronotype (LC; MEQ score = 40 ± 6) and assessed for body mass index, habitual energy intake (EI; three-day online dietary record) and eating behavior traits from the Three-Factor Eating Questionnaire (TFEQ). Participants attended the laboratory after ≥3 h fast on two occasions for early (AM; 8–10 a.m.) and late (PM; 4–6 p.m.) counterbalanced testing sessions in a 2 × 2 design. Appetite ratings and food reward (validated diurnal Leeds Food Preference Questionnaire) were measured in response to a standardized test meal. LC was associated with higher BMI (p = 0.01), but not with EI or TFEQ. The composite appetite score was lower in AM than PM (MΔ= −5 (95% CI −10, −0.2) mm, p = 0.040). Perceived test meal fillingness was higher in AM than PM and EC compared to LC (p ≤ 0.038). Liking and wanting high-fat food were lower in AM than PM (p ≤ 0.004). The late chronotype was associated with greater desire for high-fat food (p = 0.006). To conclude, early meal timing and early chronotype are independently associated with smaller appetite and lower desire for high-fat food.

Association of chronotype and pain at baseline in ovarian cancer survivors participating in a lifestyle intervention (NRG/GOG 0225).

6018 Background: Chronotype is defined as an individual’s propensity to sleep at a specific time in a 24-hour cycle with late chronotype associated with poorer health outcomes including cancer. Chronotype remains relatively undefined in ovarian cancer. The Lifestyle Intervention for oVarian cancer Enhanced Survival (LIVES) study is testing whether 1205 women randomized to a diet and physical activity intervention for 24-months will have longer progression-free survival versus an attention control. Here we determine the association of late and early vs mid chronotypes and patient reported outcomes (PROs), lifestyle behaviors and biomarkers of metabolic health and inflammation in ovarian cancer survivors post-treatment (≤ 6.5 months). Methods: Chronotype was determined using self-reported time to bed (early &lt; 9 pm; mid ≥ 9 pm - ≤12 am; late &gt; 12 am) captured through the Pittsburg Sleep Quality Index and PROs were measured using subscales of the Rand-36 questionnaire. Validated questionnaires for diet and physical activity were used and biomarkers were collected at routine clinic visits. A total subsample of 438 ovarian cancer survivors enrolled in NRG/GOG 0225- LIVES study with all available baseline measures were included in analyses. Descriptive statistics, general linear mixed models, and Pearson correlations were performed. Results: Reported pain was significantly higher in late chronotypes (P &lt; 0.05) when compared to early and mid-chronotypes. Total sleep duration was significant between the 3 chronotypes (P &lt; 0.05) with late chronotype experiencing less sleep (6.77 ± 1.67 hrs) than mid chronotype (7.04 ± 1.31 hrs) and early chronotype (7.56 ± 1.33 hrs). Higher reported pain was significantly correlated to poorer CRP levels (r = -0.198, P &lt; 0.001) suggesting higher systemic inflammation and poorer blood insulin levels (r = -0.116, P &lt; 0.05) independent of chronotype classification. All other subscales of the RAND 36 and physical activity were not associated with chronotype. Diet quality trended towards significance with a positive association observed in early and an inverse association in late chronotypes (P = 0.06). Conclusions: Late chronotypes reported higher levels of pain which was associated with poorer sleep and diet quality and higher levels of inflammation and insulin. More robust data, including actigraphy, are being analyzed and will provide additional insight of the role of circadian rhythm and phenotype on pain and key biomarkers in ovarian cancer survivors. Clinical trial information: NCT00719303.

Late Chronotype is Associated with Adolescent Asthma: Assessment Using the Korean-Version MCTQ.

Objectives: In the study, we explored whether sleep chronotypes are associated with asthma in adolescents. Methods: We analyzed 24,655 physician-diagnosed adolescent asthmatic patients and 253,775 non-asthmatic adolescent patients from the Korea Youth Risk Behavior Web-based Survey (KYRBWS). Socioeconomic factors, health behaviors factors, psychological factors, and sleep parameters were assessed using the Munich Chronotype Questionnaire (MCTQ). Logistic regression after adjusting for multiple confounders was used to explore the association between sleep chronotype and asthma. Results: The asthmatic adolescent group slept less (≤5 h: 24.3% vs. 23.2%) than the non-asthmatic adolescent group. Mean sleep duration (430.6 ± 95.6 vs. 433.5 ± 93.6 min), midpoint of sleep on school-free days (MSF; 255.9 ± 75.9 vs. 258.3 ± 73.6 min), midpoint of sleep on school days (MSW; 199.1 ± 49.1 vs. 200.1 ± 48.4 min), sleep duration on school days (SDW; 398.2 ± 98.1 vs. 400.2 ± 96.8 min), and sleep duration on school-free days (SDF; 511.8 ± 151.9 vs. 516.7 ± 147.2 min) were significantly lower, sleep satisfaction was significantly poorer (low sleep satisfaction: 41.3% vs. 37.5%), and late chronotype was significantly higher in the asthmatic adolescent (21.1% vs. 20.0%). After adjusting for multiple confounders, late chronotype was significantly associated with an increased frequency of adolescent asthma (OR 1.05; 95% CI 1.01–1.09) compared to intermediate chronotypes. Conclusions: Although our study shows a very modest association (OR of 1.05 in the fully adjusted model), we show that the late sleep chronotype is associated with asthma in adolescents in South Korea.

Social timing influences sleep quality in patients with sleep disorders

ObjectivesWe aimed to compare three variants of the Pittsburgh Sleep Quality Index (PSQI usual, work- and work-free days: PSQIu, PSQIw, PSQIf) and to assess whether chronotype (MSFsc)/social jetlag (SJL) are associated with sleep quality in patients with sleep disorders (SD). MethodsIn sum, 431 SD patients and 338 subjects from the general population (GP) were included. Participants filled in three variants of the PSQI and the Munich ChronoType Questionnaire (MCTQ). We used Generalized Estimating Equations (GEE) to investigate effects of group (GP, SD), PSQI (usual, work or free) and their interaction (group∗PSQI) on scores. To investigate associations between MSFsc/SJL and the difference between PSQIw and PSQIf (PSQIdiff) in patients with SD we used linear regressions (N = 352). We used Sobel to test whether there was a mediation effect of SJL on the association between MSFsc and PSQIdiff. ResultsPSQI scores differed between groups (p < 0.001). Post-hoc analysis revealed a significant difference between PSQIu vs. PSQIf and PSQIw vs. PSQIf with PSQIf presenting lower scores, while PSQIu vs. PSQIw did not differ in any group. In line with previous findings, SJL was associated to PSQIdiff in SD patients. ConclusionsPSQIu mainly represents sleep quality on workdays also in SD patients. Being a late chronotype seems to be associated with higher differences in sleep quality on work-vs. free days mostly when it coincides with societal time constraints. Since sleep quality is poorer on workdays even in SD patients, we suggest that treatment strategies should address social aspects affecting sleep, including ways of minimizing SJL.

Interplay of chronotype and school timing predicts school performance.

Most adolescents exhibit very late chronotypes and attend school early in the morning, a misalignment that can affect their health and psychological well-being. Here we examine how the interaction between the chronotype and school timing of an individual influences academic performance, studying a unique sample of 753 Argentinian students who were randomly assigned to start school in the morning (07:45), afternoon (12:40) or evening (17:20). Although chronotypes tend to align partially with class time, this effect is insufficient to fully account for the differences with school start time. We show that (1) for morning-attending students, early chronotypes perform better than late chronotypes in all school subjects, an effect that is largest for maths; (2) this effect vanishes for students who attend school in the afternoon; and (3) late chronotypes benefit from evening classes. Together, these results demonstrate that academic performance is improved when school times are better aligned with the biological rhythms of adolescents.

Waveform Plasticity under Entrainment to 12-h T-cycles in Drosophila melanogaster: Behavior, Neuronal Network, and Evolution.

A crucial property of circadian clocks is the ability to regulate the shape of an oscillation over its cycle length (waveform) appropriately, thus enhancing Darwinian fitness. Many studies over the past decade have revealed interesting ways in which the waveform of rodent behavior could be manipulated, one of which is that the activity bout bifurcates under environments that have 2 light/dark cycles within one 24-h day (LDLD). It has been observed that such unique, although unnatural, environments reveal acute changes in the circadian clock network. However, although adaptation of waveforms to different photoperiods is well studied, modulation of waveforms under LDLD has received relatively less attention in research on insect rhythms. Therefore, we undertook this study to ask the following questions: what is the extent of waveform plasticity that Drosophila melanogaster exhibits, and what are the neuronal underpinnings of such plasticity under LDLD? We found that the activity/rest rhythms of wild-type flies do not bifurcate under LDLD. Instead, they show similar but significantly different behavior from that under a long-day LD cycle. This behavior is accompanied by differences in the organization of the circadian neuronal network, which include changes in waveforms of a core clock component and an output molecule. In addition, to understand the functional significance of such variations in the waveform, we examined laboratory selected populations that exhibit divergent eclosion chronotypes (and therefore, waveforms). We found that populations selected for predominant eclosion in an evening window (late chronotypes) showed reduced amplitude plasticity and increased phase plasticity of activity/rest rhythms. This, we argue, is reflective of divergent evolution of circadian neuronal network organization in our laboratory selected flies.