Fatigue and mood correlates of sleep length in three age-social groups: School children, students, and employees

The aim of the study was to trace the consequences of insufficient sleep, in terms of chronic sleep reduction rather than acute sleep deprivation, on fatigue, mood, cognitive performance self-estimations, and daytime sleepiness in different age-social groups. The age group of the subjects reflects their social situation and their working time organization: adolescents (n = 191) obeyed the strict school schedules with starting times often before 08:00 h; university students (n = 115) had more flexible timetables; young employees (n = 126) were engaged in regular morning schedules or irregular daytime hours or day and night shifts. A questionnaire study determined the declared need of sleep, self-reported sleep length, chronic fatigue (using a scale comprised of eight fatigue symptoms and four mood and three cognitive items), and daytime sleepiness (Epworth Sleepiness Scale). The declared need for sleep decreased in subsequent age groups from 9 h 23 min in school children to 8 h 22 min in university students and to 7 h 37 min in young employees. Consequently, the discrepancy between preferred and real sleep length (sleep deficit) was the largest in adolescents: 106 min. Females showed a greater need of sleep than males (p = .025) and significantly more fatigue, mood, and cognitive problems; they also exhibited higher level of daytime sleepiness (p < .000). The sleep index (reported sleep length related to requirements) correlated significantly with all health issues in women (p < .000), while only with fatigue symptoms in men (p = .013). Actual sleep length was unrelated to mood and fatigue issues; the declared individual need of sleep and sleep index showed significant associations, especially in the group of adolescents. The most frequent complaints of adolescents included tiredness on awakening (46%), nervousness, and general weakness; university students reported excessive drowsiness (50%), tension, and nervousness; employees suffered mostly from negative moods, such as tension (49%), nervousness, and irritability. The findings of the study indicate that chronic sleep loss seems to affect females more severely than males. The associations of fatigue and mood with sleep need and sleep index were more pronounced in younger subjects. Surprisingly, fatigue symptoms in school children and university students were as frequent as in hard-working adults. Because the problem of insufficient sleep is already present in youngsters, their work time organization needs more attention.     

Clinical significance of social jetlag in patients with excessive daytime sleepiness

ABSTRACT

Social jetlag has recently attracted attention as the circadian misalignment between biological and social clocks. We aimed to examine social jetlag and its effect on daytime sleepiness and daily functions in patients with narcolepsy, behaviorally induced insufficient sleep syndrome (BIISS) and delayed sleep-wake phase disorder (DSPD). The levels of social jetlag (SJL_mid) and sleep-corrected social jetlag (SJL_sc) were calculated for each patient, and the effect of these social jetlag-related parameters on daytime sleepiness and daily functions were examined. Objective sleepiness measured by the mean sleep latency in the multiple sleep latency test, subjective sleepiness assessed by the Epworth sleepiness scale (ESS), health-related quality of life (HRQoL) assessed by the SF-8 health survey, and incidences of mistakes in daily activities, traffic accidents and near-miss events related to daytime sleepiness were compared among the narcolepsy (n = 39), BIISS (n = 87) and DSPD (n = 28) groups. Both SJL_mid and SJL_sc showed a negative correlation with physical HRQoL in patients with narcolepsy and a positive correlation with the ESS score in patients with DSPD. In patients with BIISS, SJL_sc reflected sleep loss rather than circadian misalignment; moreover, SJL_sc was not associated with daytime sleepiness and daily functions. Social jetlag was not associated with incidences of mistakes in daily activities, traffic accidents and near-miss events.

The state of social jetlag and its association with daily functions differed among the narcolepsy, BIISS and DSPD groups. Social jetlag represented sleep debt in BIISS, circadian misalignment in narcolepsy and both in DSPD. Our results thus show that the clinical manifestations and significance of social jetlag differ depending on the underlying sleep disorders.     

Fatigue and Mood Correlates of Sleep Length in Three Age‐Social Groups: School Children,Students, and Employees

The aim of the study was to trace the consequences of insufficient sleep, in terms of chronic sleep reduction rather than acute sleep deprivation, on fatigue, mood, cognitive performance self‐estimations, and daytime sleepiness in different age‐social groups. The age group of the subjects reflects their social situation and their working time organization: adolescents (n=191) obeyed the strict school schedules with starting times often before 08:00 h; university students (n=115) had more flexible timetables; young employees (n=126) were engaged in regular morning schedules or irregular daytime hours or day and night shifts. A questionnaire study determined the declared need of sleep, self‐reported sleep length, chronic fatigue (using a scale comprised of eight fatigue symptoms and four mood and three cognitive items), and daytime sleepiness (Epworth Sleepiness Scale). The declared need for sleep decreased in subsequent age groups from 9 h 23 min in school children to 8 h 22 min in university students and to 7 h 37 min in young employees. Consequently, the discrepancy between preferred and real sleep length (sleep deficit) was the largest in adolescents: 106 min. Females showed a greater need of sleep than males (p=.025) and significantly more fatigue, mood, and cognitive problems; they also exhibited higher level of daytime sleepiness (p<.000). The sleep index (reported sleep length related to requirements) correlated significantly with all health issues in women (p<.000), while only with fatigue symptoms in men (p=.013). Actual sleep length was unrelated to mood and fatigue issues; the declared individual need of sleep and sleep index showed significant associations, especially in the group of adolescents. The most frequent complaints of adolescents included tiredness on awakening (46%), nervousness, and general weakness; university students reported excessive drowsiness (50%), tension, and nervousness; employees suffered mostly from negative moods, such as tension (49%), nervousness, and irritability. The findings of the study indicate that chronic sleep loss seems to affect females more severely than males. The associations of fatigue and mood with sleep need and sleep index were more pronounced in younger subjects. Surprisingly, fatigue symptoms in school children and university students were as frequent as in hard‐working adults. Because the problem of insufficient sleep is already present in youngsters, their work time organization needs more attention.     

Proposal of cutoff points for pediatric daytime sleepiness scale to identify excessive daytime sleepiness

The objective of the present study was to propose cutoff points for the Pediatric Daytime Sleepiness Scale (PDSS) through sensitivity and specificity analyses in order to identify excessive daytime sleepiness, considering parameters such as duration and quality of sleep, health perception, stress control and depressive moods (feelings of sadness) in adolescents. A total of 1,132 adolescents, aged 14–19 years old, of both sexes, from the public high school of São José – SC, answered the questionnaire with information on age, daytime sleepiness, sleep duration, health perception, stress management, depressive moods (feelings of sadness) and quality of sleep. The Receiver Operating Characteristic (ROC) curve was used to estimate cutoff points considering the sensitivity and specificity values ??that best identify adolescents with excessive daytime sleepiness, using independent variables as a reference. The majority of the sample was female (54.2%), aged 14–16 years. The girls presented worse quality of sleep (66.4%), and the boys had a more positive perception of health (74.8%), better stress control (64.8%) and lower depressive moods (feelings of sadness) (63.3%). The largest area in the ROC curve was the one that considered sleep quality as a parameter in both sexes (area of the curve = 0.709 and 0.659, respectively, for boys and girls, p < 0.001). Considering sleep quality as a reference, the cutoff point for excessive daytime sleepiness was 15 points. The other parameters used were also significant (p < 0.005). Poor sleep quality was the parameter most strongly related to daytime sleepiness, and a cutoff of 15 points for the PDSS for both sexes should be used in the definition of excessive daytime sleepiness. For the other parameters, stress management, depressive mood (feelings of sadness) and health perception, different cutoff points are suggested for boys and girls.     

Sleep,School Performance,and a School-Based Intervention among School-Aged Children: A Sleep Series Study in China

Background

Sufficient sleep during childhood is essential to ensure a transition into a healthy adulthood. However, chronic sleep loss continues to increase worldwide. In this context, it is imperative to make sleep a high-priority and take action to promote sleep health among children. The present series of studies aimed to shed light on sleep patterns, on the longitudinal association of sleep with school performance, and on practical intervention strategy for Chinese school-aged children.

Methods and Findings

A serial sleep researches, including a national cross-sectional survey, a prospective cohort study, and a school-based sleep intervention, were conducted in China from November 2005 through December 2009. The national cross-sectional survey was conducted in 8 cities and a random sample of 20,778 children aged 9.0±1.61 years participated in the survey. The five-year prospective cohort study included 612 children aged 6.8±0.31 years. The comparative cross-sectional study (baseline: n = 525, aged 10.80±0.41; post-intervention follow-up: n = 553, aged 10.81±0.33) was undertaken in 6 primary schools in Shanghai. A battery of parent and teacher reported questionnaires were used to collect information on children’s sleep behaviors, school performance, and sociodemographic characteristics. The mean sleep duration was 9.35±0.77 hours. The prevalence of daytime sleepiness was 64.4% (sometimes: 37.50%; frequently: 26.94%). Daytime sleepiness was significantly associated with impaired attention, learning motivation, and particularly, academic achievement. By contrast, short sleep duration only related to impaired academic achievement. After delaying school start time 30 minutes and 60 minutes, respectively, sleep duration correspondingly increased by 15.6 minutes and 22.8 minutes, respectively. Moreover, intervention significantly improved the sleep duration and daytime sleepiness.

Conclusions

Insufficient sleep and daytime sleepiness commonly existed and positively associated with the impairment of school performance, especially academic achievement, among Chinese school-aged children. The effectiveness of delaying school staring time emphasized the benefits of optimal school schedule regulation to children’s sleep health.     

Relationships between daytime sleepiness and sleep quality,duration, and phase among school-aged children: a cross-sectional survey

A cross-sectional survey was conducted to simultaneously evaluate sleep quality, duration, and phase in school-aged children and correlations between each dimension of sleep and daytime sleepiness were comprehensively examined. A cross-sectional survey was conducted with school-aged children enrolled in four public elementary schools in Joetsu city, Niigata prefecture in Japan (n = 1683). Among the collected responses (n = 1290), 1134 valid responses (547 boys and 587 girls) were analyzed (valid response rate was 87.90%). Data on daytime sleepiness, sleep quality (problems in sleeping at night), sleep duration (the average sleeping time during a week), and sleep phase (sleep timing: bedtime and rising time on weekdays, and sleep regularity: differences in bedtime and rising time between on weekdays and weekends) were collected. The results of multivariate logistic regression analysis indicated that the following dimensions were significantly correlated with daytime sleepiness: the decline in sleep quality [adjusted odds ratio (AOR) = 2.62, 95% confidence interval (CI) = 1.71–4.00], bedtime after 21:30 on weekdays (AOR = 1.58, 95% CI = 1.15–2.18), bedtime delay on weekends, compared to weekdays (AOR = 1.75, 95% CI = 1.27–2.41), and bedtime advance on weekends, compared to weekdays (AOR = 3.33, 95% CI = 1.78–6.20). Sleep dimensions that significantly affected daytime sleepiness in school-aged children are sleep quality, bedtime-timing, and regularity of bedtime. It is important to detect problems in night sleep and establish treatments, as well as to provide support for early bedding on weekdays and for a regular bedtime both on weekdays and on weekends to prevent daytime sleepiness in school-aged children.

     

Sleep and sleepiness among working and non-working high school evening students

The aim of this study was to evaluate patterns of sleepiness, comparing working and non-working students. The study was conducted on high school students attending evening classes (19:00-22:30 h) at a public school in S?o Paulo, Brazil. The study group consisted of working (n=51) and non-working (n=41) students, aged 14-21 yrs. The students answered a questionnaire about working and living conditions and reported health symptoms and diseases. For seven consecutive days, actigraphy measurements were recorded, and the students also filled in a sleep diary. Sleepiness ratings were given six times per day, including upon waking and at bedtime, using the Karolinska Sleepiness Scale. Statistical analyses included three-way ANOVA and t-test. The mean sleep duration during weekdays was shorter among workers (7.2 h) than non-workers (8.8 h) (t=4.34; p<.01). The mean duration of night awakenings was longer among workers on Tuesdays and Wednesdays (28.2 min) and shorter on Mondays (24.2 min) (t=2.57; p=.03). Among workers, mean napping duration was longer on Mondays and Tuesdays (89.9 min) (t=2.27; p=.03) but shorter on Fridays and Sundays (31.4 min) (t=3.13; p=.03). Sleep efficiency was lower on Fridays among non-workers. Working students were moderately sleepier than non-workers during the week and also during class on specific days: Mondays (13:00-15:00 h), Wednesdays (19:00-22:00 h), and Fridays (22:00-00:59 h). The study found that daytime sleepiness of workers is moderately higher in the evening. This might be due to a work effect, reducing the available time for sleep and shortening the sleep duration. Sleepiness and shorter sleep duration can have a negative impact on the quality of life and school development of high school students.     

Sleep patterns and sleep problems among Egyptian school children living in urban,suburban, and rural areas

The present study was conducted to determine the prevalence of sleep patterns and sleep problems among Egyptian school-aged children and to compare sleep patterns and sleep problems among school children from urban, suburban, and rural areas. In this cross-sectional survey, parents of 629 school-aged children, aged 6 to 10 years, from 15 elementary schools in five rural, urban, and suburban areas in the Giza governorate, Egypt, completed the Arabic version of the Children’s Sleep Habits Questionnaire (CSHQ) and questions about parents’ level of education and significant medical problems and/or medication for the child. The mean (SD) of total sleep duration for all children was 8.96 h (SD, 1.20). The most prevalent CSHQ subscales were: bedtime resistance, daytime sleepiness, and night wakings. There were significant differences regarding bedtime (P= 0.006) and night-time sleep duration (P < 0.001) among school children from different areas, but there were no significant differences regarding wake-up time, total sleep duration, duration of nap, and the eight CSHQ subscale scores. The percentage of children who took a daytime nap was 52.9% (n= 184) and the mean (SD) duration of a nap was 1.5 h (SD, 0.92). Paternal illiteracy was associated with higher CSHQ total score and many subscales. In conclusion, sleep duration was shorter than that reported in previous studies. Sleep problems are fairly common among elementary school children in the Giza governorate, whether in urban, suburban, or rural areas. Paternal level of education has an impact on the prevalence of sleep problems.

     

Sleep and Sleepiness among Working and Non‐Working High School Evening Students

The aim of this study was to evaluate patterns of sleepiness, comparing working and non‐working students. The study was conducted on high school students attending evening classes (19:00–22:30 h) at a public school in São Paulo, Brazil. The study group consisted of working (n=51) and non‐working (n=41) students, aged 14–21 yrs. The students answered a questionnaire about working and living conditions and reported health symptoms and diseases. For seven consecutive days, actigraphy measurements were recorded, and the students also filled in a sleep diary. Sleepiness ratings were given six times per day, including upon waking and at bedtime, using the Karolinska Sleepiness Scale. Statistical analyses included three‐way ANOVA and t‐test. The mean sleep duration during weekdays was shorter among workers (7.2 h) than non‐workers (8.8 h) (t=4.34; p<.01). The mean duration of night awakenings was longer among workers on Tuesdays and Wednesdays (28.2 min) and shorter on Mondays (24.2 min) (t=2.57; p=.03). Among workers, mean napping duration was longer on Mondays and Tuesdays (89.9 min) (t=2.27; p=.03) but shorter on Fridays and Sundays (31.4 min) (t=3.13; p=.03). Sleep efficiency was lower on Fridays among non‐workers. Working students were moderately sleepier than non‐workers during the week and also during class on specific days: Mondays (13:00–15:00 h), Wednesdays (19:00–22:00 h), and Fridays (22:00–00:59 h). The study found that daytime sleepiness of workers is moderately higher in the evening. This might be due to a work effect, reducing the available time for sleep and shortening the sleep duration. Sleepiness and shorter sleep duration can have a negative impact on the quality of life and school development of high school students.     

Factors associated with sleep duration in Brazilian high school students

The aim of this study was to investigate the factors associated with short sleep duration on southern Brazilian high school students. Our study was comprised of 1,132 adolescents aged 14 to 19 years, enrolled in public high schools in São José, Brazil. The students answered a questionnaire about working (work and workload), health perception, smoking, school schedule, sleep (duration and daytime sleepiness), and socio-demographics data. The results showed that more than two thirds of adolescent workers had short sleep duration (76.7%), and those with a higher workload (more than 20 hours) had a shorter sleep duration (7.07 hours) compared to non-workers (7.83 hours). In the analysis of factors associated with short sleep duration, adolescents who worked (OR = 2.12, 95% CI 1.53 to 2.95) were more likely to have short sleep duration compared to those who did not work. In addition, older adolescents (17–19 years) and students with poor sleep quality were 40% and 55% more likely to have short sleep duration compared to younger adolescents (14–16 years) and students with good sleep quality, respectively. Adolescents with daytime sleepiness were more likely to have short sleep duration (OR = 1.49, 95% CI 1.06 to 2.07) compared to those without excessive daytime sleepiness. In addition students of the morning shift (OR = 6.02, 95% CI 4.23 to 8.57) and evening shift (OR = 2.16, 95% CI 1.45 to 3.22) were more likely to have short sleep duration compared to adolescents of the afternoon shift. Thereby adolescents who are workers, older, attended morning and evening classes and have excessive daytime sleepiness showed risk factors for short sleep duration. In this sense, it is pointed out the importance of raising awareness of these risk factors for short sleep duration of students from public schools from São José, located in southern Brazil.     

Longitudinal Change in Sleep and Daytime Sleepiness in Postpartum Women

Sleep disruption strongly influences daytime functioning; resultant sleepiness is recognised as a contributing risk-factor for individuals performing critical and dangerous tasks. While the relationship between sleep and sleepiness has been heavily investigated in the vulnerable sub-populations of shift workers and patients with sleep disorders, postpartum women have been comparatively overlooked. Thirty-three healthy, postpartum women recorded every episode of sleep and wake each day during postpartum weeks 6, 12 and 18. Although repeated measures analysis revealed there was no significant difference in the amount of nocturnal sleep and frequency of night-time wakings, there was a significant reduction in sleep disruption, due to fewer minutes of wake after sleep onset. Subjective sleepiness was measured each day using the Karolinska Sleepiness Scale; at the two earlier time points this was significantly correlated with sleep quality but not to sleep quantity. Epworth Sleepiness Scores significantly reduced over time; however, during week 18 over 50% of participants were still experiencing excessive daytime sleepiness (Epworth Sleepiness Score ≥12). Results have implications for health care providers and policy makers. Health care providers designing interventions to address sleepiness in new mothers should take into account the dynamic changes to sleep and sleepiness during this initial postpartum period. Policy makers developing regulations for parental leave entitlements should take into consideration the high prevalence of excessive daytime sleepiness experienced by new mothers, ensuring enough opportunity for daytime sleepiness to diminish to a manageable level prior to reengagement in the workforce.     

Sleep duration and social jetlag are independently associated with anxious symptoms in adolescents

Although short total sleep time (TST) is associated with increased anxious symptoms in adolescents, it is unknown whether social jetlag, a misalignment between sleep timing on the weekend and school week, is independently associated with anxious symptoms. In the current study, sleep timing, anxious symptoms, and demographic information were assessed from 3097 adolescents (48% female, mean ± SD age 15.59 ± .77 years) from the age 15 wave of the Fragile Families and Child Wellbeing Study. Social jetlag was calculated as the absolute value of the midpoint of sleep on the weekend minus the midpoint of sleep during the school week. Anxious symptoms were measured through the 6-item anxiety subscale of the Brief Symptom Inventory 18. We assessed associations between sleep variables and anxious symptoms using multiple linear regression. Adjusted analyses controlled for sex, race/ethnicity, age in years, body mass index percentile, number of other children below the age of 18 in the household, and primary caregiver (PCG) married/cohabiting with youth’s biological parent, PCG employment status, PCG household income and PCG education level. In fully adjusted models (R² = .034), school night TST (b = ?.04, ?R² = .005, p < .001) was negatively associated with anxiety symptoms, while social jetlag (b = .04, ?R² = .009, p < .001) was positively and independently associated with anxiety symptoms. Findings indicate small associations of school night TST and social jetlag with anxious symptoms. Thus, maintenance of optimal emotional health in adolescents may require both sufficient sleep duration and regularity of sleep timing across the week.     

Eveningness, sleep patterns, daytime functioning, and quality of life in Israeli adolescents

The purpose of the study was to assess the relationships between eveningness, sleep patterns, measures of daytime functioning, i.e., sleepiness, sleep problem behaviors, and depressed mood, and quality of life (QOL) in young Israeli adolescents. A cross-sectional survey was performed in urban and rural middle schools in Northern Israel. Participants were 470 eighth and ninth grade middle school students (14?±?0.8 yrs of age) in the normative school system. Students completed the modified School Sleep Habits Survey (SSHS) and Pediatric Quality of Life Inventory Short Form, assessing six subscales of physical, emotional, social, school performance, and psychosocial functioning, plus an addition generated total score. During weekdays and weekends, evening types went to bed later, their sleep latency was longer, their wake-up time was later, and their sleep duration was shorter than intermediate and morning types. Evening types exhibited more sleep problem behaviors, sleepiness, depressed mood, and lower QOL compared to intermediate and morning types. Based on the regression model, sleepiness, sleep-problem behaviors, and depressed mood were the variables most strongly associated with QOL, followed by morning-evening preference, weekday sleep duration, and weekend sleep latency. This study is the first to assess QOL in normative, healthy adolescents and to demonstrate strong associations between morning-evening preference and QOL. These findings enhance the need to identify young individuals with an evening preference, and to be aware of the characteristics and manifestations of the evening chronotype on daytime and nighttime behaviors in adolescence.     

Midpoint of sleep on school days is associated with depression among adolescents

Depression is a serious and prevalent disease among adolescents. Identifying possible factors involved with its genesis and presentation is an important task for researchers and clinical practitioners. The individual’s chronotype and social jetlag have been associated with depression in different populations. However, information on this is lacking among adolescents. The objective of this cross-sectional study was to examine the relationship between chronotype (midpoint of sleep) and social jetlag with the presence of depression symptoms in young students. We assessed 351 students aged 12–21?years old. They answered a questionnaire on demographic characteristics, the Munich Chronotype Questionnaire (MCTQ) and the Beck Depression Inventory (BDI). Demographic characteristics (age, sex and classes’ schedule) and circadian rhythmic variables for school and free days (sunlight exposure, sleep duration, midpoint of sleep and social jetlag) were taken as factors and the presence of at least mild depression symptoms as outcome. In univariate analysis, girls (χ²?=?5.01, p?≤?0.05) and evening students (χ²?=?6.63, p?≤?0.05) were more frequently present among the depressed. Also, the depression group was significantly delayed for both midpoints of sleep during school (t?=?2.84, p?≤?0.01) and free days (t?=?2.20, p?≤?0.05). The two groups did not differ in relation to their social jetlag hours (t?=??0.68, p?=?0.501) neither subjects with two or more hours of social jetlag were more frequent among the depressed (χ²?=?1.00, p?=?0.317). In multivariate analysis, the model that best explained our outcome (R²?=?0.058, F?=?2.318, p?≤?0.05) included sex (β?=??0.12, p?≤?0.05) and the midpoint of sleep on school days (β?=??0.21, p?≤?0.001) as significant predictor variables. A sleep phase delay (later midpoints of sleep for school and free days) was associated with higher levels of depression. However, we were not able to detect similar relationship with the social jetlag hours. This could be attributed to the fact that our sample showed a smaller amount of social jetlag, possibly because even during free days a social routine, this time parents’ rules, limited the observation from what could be a natural tendency to sleep later and over. Yet, even when considering the group with more social jetlag, we did not find an association. Perhaps, this variable will only manifest its effect if it is maintained for longer periods throughout life. Additionally, when considering all the variables together, the midpoint of sleep on school days was pointed as the predictor of greatest weight for depression, together with the factor sex. Young girls, possibly earlier types, who are required to study in the evening have more chances of presenting depression symptoms. This study explicit some peculiar characteristics of the assessment of chronobiological variables in the young, such as the presence of an imposed social routine also during free days. Therefore, the expression of chronotype under the influence of the weekly social schedule (midpoint of sleep on school days) could be a more useful marker to measure the stress produced from the mismatch between external and inner rhythms rather than social jetlag. This also reinforces the importance of reconsidering the weekly routine imposed on young people.     

Association between morningness and resilience in Korean college students

Circadian typology and sleep quality may be essential factors associated with the promotion of resilience. However, previous studies investigating the association between circadian typology and resilience did not analyze the effects of sleep quality on resilience. Thus, the present study evaluated the association between circadian typology and resilience in Korean college students after controlling for sleep quality. Additionally, this study investigated several sleep-related variables, including sleep duration, social jetlag and sunlight exposure during the daytime, to examine the modifiable behavioral features of morningness and also investigated whether the findings regarding morningness-related modifiable habits were associated with resilience. This study included 1094 participants (947 males and 147 females) between 19 and 29 years of age (22.8 ± 1.9 years) who completed the 10-item Korean version of the Connor–Davidson Resilience Scale (CD-RISC-10), the Korean version of the Morningness–Eveningness Questionnaire (MEQ), the Pittsburgh Sleep Quality Index (PSQI), the Korean version of the Hospital Anxiety and Depression Scale (HADS) and a survey about social jetlag that determined misalignments between weekday and weekend times of awakening and activity duration under conditions of sunlight between 10:00 and 15:00. A multiple linear regression analysis revealed that sleep duration, mean daily sunlight exposure between 10:00 and 15:00 and age were positive predictors of morningness, whereas social jetlag was a negative predictor of morningness. Of these morningness-related modifiable behavioral features, mean daily sunlight exposure between 10:00 and 15:00 significantly predicted greater resilience. An additional multiple linear regression analysis revealed that morningness was a positive predictor of resilience after controlling for age, sex, depression, anxiety and sleep quality. These results support the idea that morningness and better sleep quality are associated with greater resilience. Morningness was also associated with longer sleep duration, longer sunlight exposure during the daytime and less social jetlag, whereas longer daily sunlight exposure between 10:00 and 15:00 was associated with greater resilience. Future longitudinal studies are needed to examine whether manipulations of morningness-related modifiable behavioral features can rearrange chronotype and promote resilience.     

Role of school schedule, age, and parental socioeconomic status on sleep duration and sleepiness of Parisian children.

The aim of the study was to assess the duration and quality of sleep of prepubertal (Tanner Scale level 1) physically and mentally healthy children as a function of school schedule (4 versus 4.5 days per week), age and grade (median age of 9.5 years for 4th grade versus median age of 10.5 years for 5th grade), school district (wealthy versus nonwealthy) in Paris, France, and parental socioeconomic status (high, medium, or low). We studied 51 girl and 44 boy volunteer pupils with written parental consent. The study lasted 2 weeks during the month of March. During the first study week, the children attended school 4.5 days, and during the second week, they attended school only 4 days without difference in the length of the school day. A sleep log was used to ascertain time of lights off for sleep and lights on at awakening, nighttime sleep duration, and self-rated sleep quality. A visual analog scale (VAS) was also used by pupils to self-rate the level of perceived sleepiness at four specific times of the school day. Conventional statistical methods (e.g., t and chi2 tests) were used to examine differences in mean values. Sleep duration, self-rated sleepiness, and subjective sleep quality were comparable (P > .05) by gender, school schedule, school district, and parental socioeconomic status. Overall, the sleep of this sample of Parisian children around 10 years of age was rather stable in its duration and timing, suggesting flexibility to adjust to the different school schedules.     

Effects of Context on Sleepiness Self‐Ratings during Repeated Partial Sleep Deprivation

Ratings of subjective sleepiness are often used in laboratory and field studies of sleep loss and shifted sleep hours. Some studies suggest that such ratings might fail to reflect sleepiness as shown in physiology or performance. One reason for this may be the influence of the context of the rating. Social interaction or physical activity may mask latent sleepiness. The present study attempted to approach this question. Nine subjects participated in a partial sleep‐deprivation experiment (five days of 4 h of time in bed [TIB]), preceded by two baseline days (8 h TIB) and followed by three recovery days (8 h TIB). Sleepiness was self‐rated on the Karolinska Sleepiness Scale (KSS; scores of 1–9) after a period of relaxation, after a reaction‐time test, and after 30 min of free activities. The results showed a strong increase in subjective sleepiness during sleep restriction and a significant difference between conditions. Free activity reduced the self‐rated subjective sleepiness by 1.1 KSS units compared to the level of sleepiness self‐rated at the end of the reaction‐time test. Thus, the results of this study indicate that the context of a sleepiness rating affects the outcome of the rating.     

Circadian preference and sleep-wake regularity: associations with self-report sleep parameters in daytime-working adults

The aim of this study was to explore how interindividual differences in circadian type (morningness) and sleep timing regularity might be related to subjective sleep quality and quantity. Self-report circadian phase preference, sleep timing, sleep quality, and sleep duration were assessed in a sample of 62 day-working adults (33.9% male, age 23?48 yrs). The Pittsburgh Sleep Quality Index (PSQI) measured subjective sleep quality and the Sleep Timing Questionnaire (STQ) assessed habitual sleep latency and minutes awake after sleep onset. The duration, timing, and stability of sleep were assessed using the STQ separately for work-week nights (Sunday?Thursday) and for weekend nights (Friday and Saturday). Morningness-eveningness was assessed using the Composite Scale of Morningness (CSM). Daytime sleepiness was measured using the Epworth Sleepiness Scale (ESS). A morning-type orientation was associated with longer weekly sleep duration, better subjective sleep quality, and shorter sleep-onset latency. Stable weekday rise-time correlated with better self-reported sleep quality and shorter sleep-onset latency. A more regular weekend bedtime was associated with a shorter sleep latency. A more stable weekend rise-time was related to longer weekday sleep duration and lower daytime sleepiness. Increased overall regularity in rise-time was associated with better subjective sleep quality, shorter sleep-onset latency, and higher weekday sleep efficiency. Finally, a morning orientation was related to increased regularity in both bedtimes and rise-times. In conclusion, in daytime workers, a morning-type orientation and more stable sleep timing are associated with better subjective sleep quality. (Author correspondence: asoehner@berkeley.edu ).     

Effects of context on sleepiness self-ratings during repeated partial sleep deprivation

Ratings of subjective sleepiness are often used in laboratory and field studies of sleep loss and shifted sleep hours. Some studies suggest that such ratings might fail to reflect sleepiness as shown in physiology or performance. One reason for this may be the influence of the context of the rating. Social interaction or physical activity may mask latent sleepiness. The present study attempted to approach this question. Nine subjects participated in a partial sleep-deprivation experiment (five days of 4 h of time in bed [TIB]), preceded by two baseline days (8 h TIB) and followed by three recovery days (8 h TIB). Sleepiness was self-rated on the Karolinska Sleepiness Scale (KSS; scores of 1-9) after a period of relaxation, after a reaction-time test, and after 30 min of free activities. The results showed a strong increase in subjective sleepiness during sleep restriction and a significant difference between conditions. Free activity reduced the self-rated subjective sleepiness by 1.1 KSS units compared to the level of sleepiness self-rated at the end of the reaction-time test. Thus, the results of this study indicate that the context of a sleepiness rating affects the outcome of the rating.     

Circadian Preference and Sleep-Wake Regularity: Associations With Self-Report Sleep Parameters in Daytime-Working Adults

The aim of this study was to explore how interindividual differences in circadian type (morningness) and sleep timing regularity might be related to subjective sleep quality and quantity. Self-report circadian phase preference, sleep timing, sleep quality, and sleep duration were assessed in a sample of 62 day-working adults (33.9% male, age 23–48 yrs). The Pittsburgh Sleep Quality Index (PSQI) measured subjective sleep quality and the Sleep Timing Questionnaire (STQ) assessed habitual sleep latency and minutes awake after sleep onset. The duration, timing, and stability of sleep were assessed using the STQ separately for work-week nights (Sunday–Thursday) and for weekend nights (Friday and Saturday). Morningness-eveningness was assessed using the Composite Scale of Morningness (CSM). Daytime sleepiness was measured using the Epworth Sleepiness Scale (ESS). A morning-type orientation was associated with longer weekly sleep duration, better subjective sleep quality, and shorter sleep-onset latency. Stable weekday rise-time correlated with better self-reported sleep quality and shorter sleep-onset latency. A more regular weekend bedtime was associated with a shorter sleep latency. A more stable weekend rise-time was related to longer weekday sleep duration and lower daytime sleepiness. Increased overall regularity in rise-time was associated with better subjective sleep quality, shorter sleep-onset latency, and higher weekday sleep efficiency. Finally, a morning orientation was related to increased regularity in both bedtimes and rise-times. In conclusion, in daytime workers, a morning-type orientation and more stable sleep timing are associated with better subjective sleep quality. (Author correspondence: asoehner@berkeley.edu)