Sleep duration and chronotype in adults in Côte d'Ivoire: influence of gender,religion and age

This study investigated the sleep-wake rhythm and chronotype of people living in Côte d'Ivoire. We assessed sleep-wake behaviour in 556 adults (336 men, 220 women) between 25 and 54 years (mean: 38.63) by means of structured interviews. Data were analysed by linear models with sleep wake variables as dependent variables and age, gender, religion and region (urban/rural) as fixed factors controlling for number of working hours and children. Results suggest sleep length not to differ between weekdays and weekends but sleep timing (chronotype) was later on weekends with a midpoint of sleep at 1:37am during weekdays compared to 1:58am on weekends. The more children, the earlier was the midpoint of sleep and the shorter was sleep length. Midpoint of sleep was earlier in older people. Women slept longer during weekdays and were earlier chronotypes. Sleep duration was longer in the rural areas and midpoint of sleep was later in the urban areas on weekdays and on the weekend. Muslims showed the shortest sleep duration and were earliest chronotypes. Sleep-wake cycles in the African setting sample were shorter for women, Moslems, and older people.     

Assortative mating in morningness-eveningness

Individuals differ in their morningness-eveningness preference (circadian preference); that is, some prefer morning hours for intellectual and physical activities and others prefer late afternoon or evening hours. This has been viewed as an interesting facet of personality. Assortative mating has been studied in personality research, but assortative mating in circadian preference has rarely been examined. Eighty-four couples participated in this study. They filled in the Composite Scale of Morningness; they also supplied data about rise times and bedtimes as well as information about relationship satisfaction and duration. The results revealed a moderate positive relationship between couple partners in morningness-eveningness which persisted after correcting for age. Similarly, correlations existed between the sleep-wake variables (rise time and bedtime) on weekdays and on the weekends, the association being higher for weekends. There was no significant correlation between length of the relationship and dissimilarity in morningness-eveningness, suggesting that the above-reported correlations reflect an initial assortment rather than convergence effects. Further, no significant correlation was found between dissimilarity in morningness-eveningness and relationship satisfaction. The results suggest that assortative mating in morningness-eveningness is likely and is probably based on an initial assortment. The likelihood to meet and mate may also be linked to chronotype. When differences in circadian preferences exist between possible partners, this reduces the likelihood that these persons meet either by accident or during work and leisure activities. Therefore, two extreme chronotypes are unlikely to meet each other because they have the smallest overlap in their preferred active time during the day due to the circadian rhythmicity.     

Cross‐cultural comparison of seven morningness and sleep–wake measures from Germany,India and Slovakia

Morningness–eveningness or circadian typology can be viewed as an interesting aspect of individual differences. Morningness–eveningness is a preference for a given time of day for physical or mental performance, but also reflects aspects of affect. Here, we used seven different measures to assess differences in morningness–eveningness between Germany, Slovakia and India. The hypothesis was that Indians should be earliest chronotypes, followed by Slovakia and then Germany, because of higher temperatures in India, and the fact that Slovakia is located farther east compared to Germany. We applied the Composite Scale of Morningness (CSM), the Circadian Energy Scale (CIRENS), the CAEN Chronotype Questionnaire (CCQ), and habitual sleep–wake variables to calculate sleep duration, midpoint of sleep and social jetlag. Sample sizes were N = 300 (Germany), N = 482 (Slovakia) and N = 409 (India). Country had the strongest influence on morningness–eveningness. Germans were latest chronotypes and differed in all seven measures from Indians but differed from Slovakians only in the energy level at the evening and midpoint of sleep. Slovakians and Indians differed in all measures but the energy level (CIRENS). Women scored higher on the CSM, lower on CIRENS, lower on the morningness–eveningness (ME) scale, but higher on distinctness (DI) scale. Women slept longer and had an earlier midpoint of sleep.     

Trends in timing of sleep in the general population of Norway: 1980 to 20001

The aim of the current study was to examine whether the timing of sleep have changed over the last two decades. As part of a general survey of activities throughout the 24-hr. cycle, collected in 1980, 1990, and 2000 by Statistics Norway, information on sleep timing was obtained for every 15-min. interval for 1 wk. All three samples were representative of Norwegians. The age span was from 16 to 74 years. Timing of sleep was significantly delayed in 2000 compared to 1990 and especially so in 1980, but with no change in total amount of sleep. From 1980 to 2000, there was an increasing discrepancy in sleep or wake timing between weekdays and weekends. The current analyses show that people sleep as much as before but do so at different times. The increased discrepancy between weekdays and weekends indicates that overall sleep habits are poorer now than previously.     

The Chronotype-Academic Performance Model (CAM): Daytime sleepiness and learning motivation link chronotype and school performance in adolescents

Many adolescents experience a discrepancy between their biological time, which is shifted toward eveningness, and early school starting times. Due to this social jetlag, eveningness is negatively correlated with school performance. On the basis of the here presented data, we derived a model for the association of chronotype and school performance, the Chronotype-Academic Performance Model (CAM), including daytime sleepiness and achievement motivation as mediating factors. The sample comprised N = 273 adolescents aged 14–16 years. Circadian preference, daytime sleepiness, learning and achievement motivation, and information about participants’ last school certificate were assessed online. Chronotype was not directly related to academic performance, but was mediated by daytime sleepiness and learning motivation. Morning-orientation was negatively associated with daytime sleepiness and positively with learning motivation, which, in turn, affected performance. In evening-types, we found the strongest association between sleepiness and refusal to work. The CAM suggests that chronotype may not directly influence academic performance, but be mediated by daytime sleepiness and learning motivation. Evening types seem to be at high risk to suffer from daytime sleepiness and to display dysfunctional attitudes toward work. Measures of reducing sleepiness and modifying attitudes toward academic achievement might attenuate the disadvantages of evening-types due to social jetlag.     

The effect of a delayed weekend sleep pattern on sleep and morning functioning

Abstract

It is a common practice for young adults to delay their weekend sleep schedule. The present study was designed to assess the effect of this sleep pattern on the sleep of Sunday night and the functioning of Monday morning. The sleep schedules of 30 young adults were manipulated for 2 consecutive weeks. In the Habitual-Sleep (HS) week, subjects followed their habitual sleep schedule throughout the week; in the Delayed-Sleep (DS) week, subjects' sleep schedule on Friday and Saturday nights were delayed by two hours. Compared to the HS week, subjects showed significantly lower subjective sleepiness near bedtime and trends of longer sleep onset latency on Sunday night in the DS week. In addition, there was both lowered cognitive performance and overall mood rating on Monday morning in the DS week. The delayed weekend sleep pattern contributes to Sunday night insomnia and the Monday morning “blues”.     

日周期类型与心理健康

个体间表现出的昼夜节律差异现象可以从日周期类型上进行分类, 包括偏爱早睡早起的清晨型, 偏爱晚睡晚起的夜晚型以及处于两者之间的中间型。已有研究表明, 夜晚型与心境障碍、注意缺陷多动障碍和进食障碍等心理疾病有关, 而日周期类型与心理健康的关系可能受到基因、社会时差、人格等因素的影响。未来应改进研究设计和测量方法, 深入考察日周期类型与心理健康的关系及其作用机制, 以及在我国文化背景下推进日周期类型与心理健康的关系研究。     

Screen use before bedtime: Consequences for nighttime sleep in young children

There is increasing interest in the relation between screen use and sleep problems in early childhood. In a sample of 30-month-old children, this study used observational measures of screen use during the hour or so leading up to bedtime, parent reports of screen use during the child’s bedtime routine, and actigraphic measures of toddler sleep to complement parent-reported sleep problems. Whether screen use was observed during the pre-bedtime period or was reported by the parents as part of the nightly bedtime routine, greater screen use in either context was associated with more parent-reported sleep problems. Additionally, more frequent parent-reported screen use during the bedtime routine was also associated with actigraphic measures of later sleep, shorter sleep, and more night-to-night variability in duration and timing of sleep. These associations suggest the negative consequences of screen use for children’s sleep extend both to aspects of sleep reported by parents (e.g., bedtime resistance, signaled awakenings) and to aspects measured by actigraphy (e.g., shorter and more variable sleep).     

Non‐standard work schedules and retention in the entry‐level hourly workforce

Non‐standard work schedules involve work outside the Monday–Friday daytime hours. Although research has heavily studied the health and family effects of such schedules, few studies have investigated their relationship to retention. We draw from Maertz and Campion's discussion of motivational forces that influence turnover to propose that employees on non‐standard schedules are more likely to quit their employer because of general job dissatisfaction and because of normative pressures from family and/or friends. Specifically, we hypothesized that employees on day shifts or weekday only schedules would remain with their employer longer than those who work on nonday shifts or on the weekends. We also hypothesized that perceived employment mobility would moderate the effects of non‐standard schedules on retention length. Hypotheses were tested among 3,178 retail employees who worked five different distinct shift arrangements and different weekday/weekend schedules. Cox regression analyses indicated that, as hypothesized, employees working nonday shifts or schedules including weekends remained with their employer for a shorter duration of time than employees not on such schedules. Perceived mobility moderated the schedule–turnover relationship, though not in the hypothesized manner. We discuss the theoretical and practical implications of these findings for work schedule assignment and retention strategies.     

Activity involvement among suicidal and nonsuicidal high-risk and typical adolescents

The purpose of this study was to compare weekly activities among four groups of randomly selected high-risk and typical high school students: (1) potential dropouts at suicide risk, (2) typical youth at suicide risk, (3) potential dropouts not at suicide risk, and (4) typical youth not at suicide risk. Of the 1,286 participants, 39.4% of the high-risk and 30.1% of typical high school students screened in at suicide risk. Weekly activity comparisons across the four groups showed that suicide-risk adolescents, regardless of potential dropout status, engaged in more solitary activities on weekdays and weekends than did their nonsuicide risk peers. High-risk potential dropout youth engaged in less homework and more social activities during weekdays and weekends than did the typical high school students. These results provide important insight into the weekly activity involvement of at-risk youth while helping to gain a better understanding of suicide-risk adolescents. Implications of these findings are discussed for identifying youth at risk for suicidal behavior and for prevention programming.     

Self-control depletion and sleep duration: the mediating role of television viewing

Abstract

Objective: Sleep insufficiency has been related to self-control failure: people fail to go to bed in time and end up sleep deprived. The role of state self-control in predicting bedtime and sleep duration has not yet been investigated. Based on research claiming an overlap between depleted self-control resources and fatigue, self-control depletion may foster earlier bedtimes. Conversely, self-control depletion also increases the propensity to procrastinate bedtime by giving in to the immediate gratification of late night entertainment. This study therefore looked at procrastinatory television viewing and its intermediary role in the association between state self-control and bedtime. The implications for sleep duration are examined. Design: Firstyear students (N = 234) participated in an online survey. Using Day Reconstruction Method, they charted their activities and experiences during the preceding day and subsequent bedtime behavior. Results: Self-control depletion was directly related to earlier bedtimes, which we explained by its similarity to fatigue. This was associated with longer sleep duration. Self-control depletion was indirectly related to later bedtimes because it increased the propensity to procrastinate by watching television. This was associated with shorter sleep duration. Conclusion: This study exposes a dual pathway between self-control depletion and sleep duration, whereby procrastinatory television viewing may reduce sleep duration.     

Morningness-eveningness in adolescents

Individual morningness-eveningness differences explain the rhythmic variations of behavioral and biological patterns. Several studies have corroborated that morningness preference increases over adulthood and aging. Adolescents shift their time of day preferences from morningness to eveningness during puberty. The aims of this study were translate to Spanish the Morningness-Eveningness Scale for Children (MESC) and to analyze age and sex differences. A group of 600 adolescents (aged between 12 and 16 years) participated in the study. Psychometric analysis showed that reliability and factor structure were suitable and similar to previous studies. The results indicated a clear decrease of morningness as of 12 years. Boys were more morningness-oriented than girls in several items of the questionnaire. In view of the results, several educational implications are raised.     

The sleep patterns and problems of clinically anxious children

Childhood sleep problems have been associated with a range of adverse cognitive and academic outcomes, as well as increased impulsivity and emotional disorders such as anxiety and depression. The aim of the study was to examine subjective reports of sleep-related problems in children with anxiety disorders during school and weekend nights. Thirty-seven children with clinically-diagnosed anxiety disorders and 26 non-clinical children aged 7-12 years completed an on-line sleep diary to track sleep patterns across school nights and weekend nights. Anxious children reported going to bed significantly later (p = 0.03) and had significantly less sleep (p = 0.006) on school nights compared to non-anxious children. No significant differences in sleep onset latency, number of awakenings or time awake during the night, daytime sleepiness, or fatigue were found between the two groups. On the weekends, anxious children fell asleep quicker and were less awake during the night than on weeknights. School-aged anxiety disordered children showed a sleep pattern that differs from their non-anxious peers. Although the mean 30 min less sleep experienced by anxious children may initially seem small, the potential consequences on daytime performance from an accumulation of such a sleep deficit may be significant, and further investigation is warranted.     

Association between morningness-eveningness and mental and physical health in adolescents

Individuals differ in their biological rhythms and their preference for morning or evening hours. Morning types prefer morning hours for intellectual and physical activities while evening types feel and perform best at late afternoon or in the evening. This not only is a simple dichotomous classification but also can be viewed as a continuum. Individual differences in morningness-eveningness are an interesting facet of personality, but little is known about the relationship between psychological factors or health-related variables and morningness-eveningness in adolescents. In Study I, there were positive correlations between morningness and positive attitude towards life and a negative association between morningness and depression. In Study II, there were significant positive relationships between morningness and physical health, mental health, self-esteem, familial relationship, and school functioning. These results indicate that eveningness might be an unspecific risk factor for mental and physical health.     

Predicting school achievement: The role of inductive reasoning,sleep length and morningness–eveningness

Adolescents move to evening orientation just when school schedule becomes earlier. Whereas school achievement has been associated to morningness orientation during morning school schedule, some studies have indicated that evening people are more intelligent. In this study the relative contribution of Morningness–Eveningness (M–E) in the prediction of school achievement, after controlling for age, sex/gender, inductive reasoning and sleep length was analyzed. Participants were 887 adolescents (aged 12–16). School achievement was evaluated using Grade Point Average (GPA), inductive reasoning was evaluated by reasoning subtest of Primary Mental Abilities (PMA-R), sleep length was calculated from rise time and bedtime questions, and M–E was evaluated by Morningness–Eveningness Scale for Children (MESC). Evening adolescents scored higher on PMA-R and obtained lower GPA. Inductive reasoning, age, sex/gender, sleep length and M–E accounted for 19% variance percentage on GPA. M–E was a significant predictor of school achievement even after controlling for traditional predictors, albeit slightly.     

Sleep variability and fatigue in adolescents: Associations with school‐related features

This study aims to evaluate the influences of sleep duration and sleep variability (SleepV), upon adolescents' school‐related situations. The Health Behaviour in School‐Aged Children (HBSC) survey is based on a self‐completed questionnaire. The participants were 3164 pupils (53.7% girls), attending the 8th and 10th grades, 14.9 years old, and were inquired about subjective sleep duration during the week and weekends, SleepV, fatigue, difficulties in sleep initiation, school achievement, feelings towards schools, pressure with school work and skipping classes. Multiple regression models used, as dependent variables: (a) school achievement, (b) disliking school, (c) pressure with school work and (d) skipping classes, using as independent variables, each of the remaining school‐related variables, fatigue, total sleep duration and difficulties in sleep initiation. The average sleep duration in the week and during weekdays was lower than recommended for these age groups, and almost half of students had high SleepV between weekdays and weekends. A logistic model revealed that the absence of SleepV was associated with lower perception of school work pressure, less frequent skipping classes, more infrequent fatigue and more infrequent difficulties in sleep initiation. Poor sleep quality, SleepV and insufficient sleep duration affected negatively school‐related variables.     

Effectiveness of an mHealth Intervention for Infant Sleep Disturbances

Bedtime problems and night wakings are highly prevalent in infants. This study assessed the real-world effectiveness of an mHealth behavioral sleep intervention (Customized Sleep Profile; CSP). Caregivers (83.9% mothers) of 404 infants (age 6 to 11.9 m, M = 8.32 m, 51.2% male) used the CSP (free and publicly available behavioral sleep intervention delivered via smartphone application, Johnson’s® Bedtime® Baby Sleep App). Caregivers completed the Brief Infant Sleep Questionnaire–Revised (BISQ-R) at baseline and again 4 to 28 days later. Changes in sleep patterns were analyzed, based on sleep problem status (problem versus no problem sleepers; PS; NPS). Sleep onset latency improved in both groups. Earlier bedtimes, longer continuous stretches of sleep, as well as decreased number and duration of night wakings, were evident in the PS group only. The BISQ-R Total score, total nighttime sleep, and total 24-hour sleep time improved for both groups, with a greater change for the PS group. Further, caregivers of infants in the PS group decreased feeding (bedtime and overnight) and picking up overnight, and perceived better sleep. Bedtime routine regularity, bedtime difficulty, sleep onset difficulty, and caregiver confidence improved for both groups, with the PS group showing a greater magnitude of change. Thus, a real-world, publicly available, mHealth behavioral sleep intervention was associated with improved outcomes for older infants. Intervention recommendations resulted in changes in caregivers’ behavior and improvements in caregiver-reported sleep outcomes in infants, in as few as 4 days.     

Exploring Socioeconomic Differences in Bedtime Behaviours and Sleep Duration in English Preschool Children

Children's sleep is critical for optimal health and development; yet sleep duration has decreased in recent decades, and many children do not have adequate sleep. Certain sleep behaviours (‘sleep hygiene’) are commonly recommended, and there is some evidence that they are associated with longer nighttime sleep. Parents of 84 British 3‐year‐old children were interviewed about their children's sleep and completed five‐night/four‐day sleep diaries documenting their children's sleep, from which daily sleep duration was estimated. Diaries were validated by actigraphy in a subgroup of children. Sleep hygiene behaviours (regular bedtime, reading at bedtime, falling asleep in bed) were associated with each other, and were more common in the high socioeconomic status compared to the low socioeconomic status group. Parents' reasons for not practicing sleep hygiene included difficulty, inability or inconvenience. Sleep hygiene behaviours were associated with significantly longer child sleep at night but not over 24 h. Longer daytime napping compensated for shorter nighttime sleep in children whose parents did not implement sleep hygiene behaviours. Parents may need to be advised that certain behaviours are associated with longer nighttime sleep and given practical advice on how to implement these behaviours. © 2014 The Authors. Infant and Child Development published by John Wiley & Sons, Ltd.     

Morningness-eveningness, use of stimulants, and minor psychiatric disorders among undergraduate students

Morningness–eveningness dimension in humans have been indicated to influence social behavior and individual health. The aim of the present study was to investigate the association of the morningness–eveningness dimension with behavioral and health aspects in a sample of undergraduate students. We assessed demographic data; the Pittsburgh Sleep Quality Index was used to evaluate sleep quality; the Morningness/Eveningness Questionnaire to determine morningness–eveningness, and the Self‐Reporting Questionnaire to assess minor psychiatric disorders. A total of 372 students (66.7% females), on average 21.6 years old, participated in this study. Among them, 92.2% did not smoke, 58.9% engaged in physical activities, and 19.7% were night‐shift workers. In regard to morningness–eveningness, 55.9% of the participants were intermediate between evening (39.5%) and morning (4.6%) types. Poor sleep quality (OR = 1.89), minor psychiatric disorders (OR = 1.92), and tobacco consumption (OR = 3.65) predominated among evening types. Evening types were predominantly males (OR = 1.72). This study suggests that evening types are more vulnerable to sleep and psychiatric disturbances, and tend to smoke more than morning types.     

What Motivational and Awareness Variables are Associated with Adolescents’ Intentions to Go to Bed Earlier?

The aim of the study was to test the motivation and awareness variables of the I-change model as predictors of adolescent intention to go to bed earlier. Questionnaires regarding sleep related motivational and awareness variables were administered to 127 sleep restricted (determined by actigraphy) high school students (12–17 years old). The motivational variables positive attitudes towards sleep and parents setting wake time predicted higher intentions to go bed earlier. The awareness variable sleep related cues to action also predicted higher intentions to advance bedtime. Positive attitudes towards sleep partially mediated the effect of sleep related cues to action on intention to advance bedtime. Future sleep promotion programs should train adolescents to detect cues to go to bed earlier to increase their intentions to go to bed earlier. Adolescents should be assisted to develop positive attitudes towards sleep as to enhance their autonomous motivation to advance their bedtime.