Comparison of dream anxiety and subjective sleep quality between chronotypes

Morning and evening-type individuals differ on a number of psychological and biological variables. In this study, we aimed to investigate the relationship between sleep quality, dream anxiety, and chronotypes. A sample of 264 university students, aged between 17 and 26 years, completed the Morningness-Eveningness Questionnaire, the Pittsburgh Sleep Quality Index, and the Van Dream Anxiety Scale for assessing nightmare frequency and the dream anxiety caused by frightening dreams. Main findings indicated that evening-type individuals were significantly more likely to suffer from poor sleep quality, daytime dysfunction, nightmares, and nightmare-related disturbances as compared to either intermediate- or morning-type individuals. Previous studies have pointed out the possible connections of irregular sleep-wake habits and circadian dysregulation with a tendency to reveal eveningness chronotypical characteristics. Current findings suggest that evening-type individuals are more prone to experience psychologically deteriorating nightmares and sleep-related anxiety. Poor sleep quality is also a significant antecedent of dream anxiety after controlling for age and gender.

     

Chronotype and its relationship with sleep disorders in children with attention deficit hyperactivity disorder

Chronotype can be classified as morningness types, people who prefer morning hours for their physical and mental activities; eveningness types, people who prefer the afternoon or evening hours; and intermediate types, those who show characteristics of both morningness and eveningness types. Attention deficit hyperactivity disorder (ADHD) has been linked with disturbances in chronotype, particularly increased eveningness. Despite the possibility of an association between chronotypes, sleep disturbances and ADHD symptoms, there is little evidence of this association considering the child population. The purpose of this study was to examine chronotype preferences in children aged between 7 and 12 years who were diagnosed as having ADHD in the context of sleep disturbances. The Schedule for Affective Disorders and Schizophrenia for School Age Children-Present and Lifetime Version, Conner’s Rating Scales, Children’s Sleep Habit Questionnaire and Children’s Chronotype Questionnaire were used for the evaluation of children with ADHD and healthy controls. The ADHD group was 73% combined-type, and the eveningness scores of the ADHD group (n = 52) were significantly higher than the control group (n = 52) (p < 0.01). There was a positive correlation between the higher scores of eveningness and total scores on resistance to sleep time (p < 0.09), respiratory problems during sleep and daytime sleepiness in the ADHD group. CSHQ total score was found to be a predictive factor for eveningness among children with ADHD (p < 0.01). These findings highlight possible reciprocal links between ADHD symptoms, sleep disturbances and chronotype in children aged 7–12 years, which might lead to individualized treatment options.     

Effects of chronotype and environmental factors upon sleep and mental health in Japanese students aged 18–40 yrs

An integrated questionnaire was administered to a total of 4142 (2137 women, 2005 men; answer rate: 94.4%) university students and medical training schools students aged 18–40 years. The survey was carried out between May and October, 2004–2013. This questionnaire consisted of assessment of diurnal type, questions on sleep habits, mental health (upset emotionally, irritated, angered by small triggers, and suppressed), frequency of watching TV at night, use of mobile phone and playing TV games between 21:00 and 03:00 h, and questions on lighting conditions during the daytime and night. Sleep length in evening-type students (E-type; diurnal-type scores = 7–12) was shorter than in intermediate-types (I-type; diurnal-type scale (DTS) = 13–16) and morning-types (M-type; DTS = 17–28) on weekdays (p < 0.001), whereas sleep length in evening-types was shorter than intermediate- and morning-type students at weekends (p < 0.001). Mental health index scores of the E-type students were significantly lower than those of I-type and M-type students in both sexes (p < 0.001). Seventy-three percent of E-type women students watched TV after 23:00 h, significantly higher than 65.0 and 52.5% of I-type and M-type females, respectively (p < 0.001), and 70.4% of E-type male students watched the TV after 23:00 h, significantly higher than 66.1 and 59.7% of I-type and M-type males, respectively (p = 0.001). With regard to lighting conditions in the room in the afternoon, a slightly lower, but significantly so, percentage of the E-type students used the sunlight coming through the window than did the other types (p < 0.001). The frequency of having three nutritionally rich meals (especially breakfast) – including carbohydrates, proteins, vitamins, and minerals – was significantly higher in M-type than I-types and E-types (p < 0.001). Premenstrual syndrome (PMS) was significantly more severe in E-type than I-type and M-type females (p = 0.002). Lighting conditions throughout the 24 h and at breakfast can act as a strong zeitgeber for students and exert a great influence on their mental and physical health and can also affect PMS in women students.     

Relationships Among Circadian Typology,Psychological Symptoms,and Sensation Seeking

Recently, attention has been focused on the relationship among circadian typology, psychiatric symptoms, and personality traits. This study analyzes the influence of circadian typology on psychological distress, and the sensation-seeking personality trait. Five hundred seventeen college students (173 males), aged 17 to 30, answered the Composite Scale of Morningness (CSM), the General Health Questionnaire 28-item version (GHQ-28), and the Sensation Seeking Scale-V (SSS-V). The evening-type subjects in our sample scored higher than the neither- and morning- type in the GHQ-28 total score, as well as in the four subscales that composed it (Psychosomatic Symptoms, Anxiety and Insomnia, Social Dysfunction, and Severe Depression) (p?<?0.02 in all cases). The evening-type subjects also had a larger proportion of psychiatric cases than the other two circadian typologies (p?<?0.0001 in all cases). Moreover, the evening-type subjects obtained higher scores in the SSS-V total score and in the subscales of Disinhibition and Boredom Susceptibility (p?<?0.001 in all cases). A positive correlation was observed between the GHQ-28 and the SSS-V total scores in the total sample, but only for the evening-type group (r?=?0.217; p?<?0.027). In the evening group, several relations were also found between the subscales of the GHQ-28 and the subscales of the SSS-V (r?>?0.206; p?<?0.036). All these data point to a relationship between evening-type subjects and the level of psychological distress and the sensation-seeking personality trait. They also suggest that eveningness could be related to developing psychological distress and personality traits that could, in turn, be related to developing other problems, such as drug consumption.     

Eveningness as a risk for behavioral problems in late adolescence

Circadian preference toward eveningness has been associated with increased risk for mental health problems both in early adolescence and in adulthood. However, in late adolescence, when circadian rhythm naturally shifts to later, its significance for mental health is not clear. Accordingly, we studied how circadian rhythm estimated both by self-reported chronotype and by actigraph-defined midpoint of sleep was associated with self-reported psychiatric problems based on Youth Self Report (YSR). The study builds on a community cohort born in 1998, Helsinki, Finland. At age 17 years (mean age = 16.9, SD = 0.1 years), 183 adolescents (65.6% of the invited) participated in the study. We used the shortened version of the Horne-Östberg morningness–eveningness Questionnaire to define the chronotype, and actigraphs to define the naturally occur circadian rhythm over a 4 to 17 days’ period (mean nights N = 8.3, SD = 1.8). The Achenbach software was used to obtain T-score values for YSR psychiatric problem scales. The analyses were adjusted for important covariates including gender, socioeconomic status, body mass index, pubertal maturation, mother’s licorice consumption during pregnancy, and actigraph-defined sleep duration and quality. Eveningness was associated with higher scores in rule-breaking behavior and conduct problems (as assessed either by midpoint of sleep or by self-reported chronotype, p-values <0.05), attention deficit/hyperactivity problems (by self-reported chronotype, p-values <0.05), with affective problems (by midpoint of sleep and by self-reported chronotype, p-values <0.05) and somatic complaints (by self-reported chronotype, p-values <0.05), as compared to circadian tendency toward morningness. Our results suggest that the association between eveningness and externalizing problem behavior, present in children and younger adolescents, is also present in late adolescence when circadian rhythms shift toward evening.     

Chronotype,bed timing and total sleep time in seniors

Many older adults (seniors) experience problems with getting enough sleep. Because of the link between sleep and circadian rhythms, changes in bedtime lead to changes in the amount of sleep obtained. Although primarily determined genetically, chronotype changes with advancing age towards a more morning-type (M-type) orientation. In a 2006 study, we have found a linear relationship, by which the earlier a senior’s bedtime, the more sleep she/he will obtain. The aim of this study was to see whether this relationship differs for M-type seniors, as compared to seniors outside the M-type category. Retired seniors (n?=?954, 535?M, 410F, 65?years+, mean age 74.4?years) taking part in a telephone interview were divided into M-types and Other types (O-types) using the Composite Scale of Morningness (CSM). The relationship between bedtime and Total Sleep Time (TST), and between rise-time and TST, was tested using linear regression separately for M-types and O-types. For each participant, habitual bedtime, rise-time and total Sleep Time (TST) [after removing time spent in unwanted wakefulness] were obtained using a telephone version of the Sleep Timing Questionnaire (STQ). Both chronotype groups showed a significant linear relationship between bedtime and TST (p?<?0.001); with earlier bedtimes leading to more TST (M-type 5.6?min; O-type 4.4?min per 10?min change [slope difference p?=?0.05]); and an opposite relationship between rise-time and TST with earlier rise-times leading to less TST (M-type 6.7?min; O-type 4.2?min per 10?min change [slope difference p?=?0.001]). M-types retired to bed 56?min earlier (p?<?0.001), awoke 93?min earlier (p?<?0.001) and obtained 23?min less TST (p?<?0.001) than O-types. In conclusion, both chronotypes showed TST to be related in a linear way to bedtime and rise-time; the overall shorter TST in M-types was due to them rising 93?min earlier, but only retiring to bed 56?min earlier than O-types; as well as having a steeper rise-time versus TST relationship.     

The impact of a delayed sleep–wake schedule on depression is greater in women – A web-based cross-sectional study in Japanese young adults

Sleep-related problems, such as symptoms of insomnia, daytime sleepiness, shorter sleep duration, or a delayed sleep–wake schedule, are known to be risk factors for depression. In general, depression is more prevalent in women than in men, but sleep-related problems do not necessarily show similar gender predominance. Hence, it can be speculated that the impact of sleep-related problems on the development process of depression differs between genders; however, so far, few studies have focused on this issue. The aim of this study was to clarify gender differences in the rates of depression of people with the above sleep-related problems, and to examine gender differences in factors associated with depression in Japanese young adults. A web-based questionnaire survey comprising assessments of demographic variables, sleep-related variables (bed time, wake time, sleep onset latency, frequency of difficulty in initiating sleep and that in maintaining sleep, i.e. symptom components of insomnia, and daytime sleepiness), and the 12-item version of the Center for Epidemiologic Studies Depression Scale was administered to 2502 participants (males:females?=?1144:1358, age range?=?19–25 years). Female predominance in the rate of depression was observed only in subjects with a delayed sleep–wake schedule (χ²₍₁₎?=?15.44, p?<?0.001). In men, daytime sleepiness and difficulty in initiating sleep were significantly associated with depression (odds ratio [OR]?=?2.39, 95% confidence interval [CI]?=?[1.69, 3.39], p?<?0.001; OR?=?3.50, 95% CI?=?[2.29, 5.35], p?<?0.001, respectively), whereas in women, significant associations were found between depression and a delayed sleep–wake schedule (OR?=?1.75, 95% CI?=?[1.28, 2.39], p?<?0.001), daytime sleepiness (OR?=?2.13, 95% CI?=?[1.60, 2.85], p?<?0.001), and difficulty in initiating sleep (OR?=?4.37, 95% CI?=?[3.17, 6.03], p?<?0.001). These results indicate that in younger generations, the impact of a delayed sleep–wake schedule on the development of depression is greater in women; specifically, women are vulnerable to depression when they have an eveningness-type lifestyle, which is possibly attributable to the female-specific intrinsic earlier and shorter circadian rhythm. These results suggest the necessity of gender-based approaches to treating sleep-related problems for alleviating or preventing depressive symptoms in young adults.     

Influence of Chronotype,Season, and Sex of Subject on Sleep Behavior of Young Adults

The aim of this study was to investigate whether sex, season, and/or chronotype influence the sleep behavior of university students. Detailed data were collected on activity/rest patterns by wrist actigraphy combined with diaries. Thirty‐four medical students (19 female and 15 male) were monitored by Actiwatch® actometers for 15 consecutive days in May and again in November. The data of a modified Horne and Östberg chronotype questionnaire, which were collected from 1573 female and 1124 male medical school students surveyed in the spring and autumn over an eight‐year period, were evaluated. Actiwatch® sleep analysis software was used to process the activity data with statistical analyses performed with ANOVA. We found no significant sex‐specific differences in sleep efficiency, sleep onset latency, or actual sleep‐time duration. However, we did find a difference in sleep efficiency between morning and evening types, with morning types having a higher sleep efficiency (87.9%, SD=1.3) than evening types (84.3%, SD=0.87%; p=0.007). Seasonal differences were also detected: the actual sleep‐time duration in autumn was significantly longer (mean 6.9 h, SD=0.13 h) than in spring (6.6 h, SD=0.1 h; p=0.013). Evaluation of the chronotype questionnaire data showed that individuals with no special preference for morningness or eveningness (i.e., so‐called intermediates) were most common. The distribution of chronotypes was related to the sex of subject. Men displayed eveningness significantly more often than women (28.9% males vs. 20.8% females; p<0.001), while females exhibited greater morningness (20.3% females vs.15.6% males; p<0.001). Sex influences chronotype distribution, but not actual sleep time‐duration, sleep onset latency, or sleep efficiency. The latter, however, differed among chronotypes, while actual sleep‐time duration was affected by season.     

Association of Eveningness With Problem Behavior in Children: A Mediating Role of Impaired Sleep

Eveningness, the preference of being active during the evening in contrast to the morning, has been associated with markedly increased problem behavior in adolescents; however, the underlying mechanisms are still not understood. This study investigates the association of eveningness with behavior and cognition in children aged 7–12 yrs, and explores the potential mediating role of a variety of sleep factors. Parents of 333 school-aged children (mean age?=?9.97 yrs; 55% girls) completed a sleep log and several questionnaires regarding eveningness, sleep habits, and behavioral problems. Intellectual abilities, working memory, and attention were assessed using the short-form of the Wechsler Intelligence Scale for Children (WISC) and subtasks of the Amsterdam Neuropsychological Tasks. Results showed that eveningness predicted behavioral problems over and above the effects of demographic variables (age, sex, and familial socioeconomic status) (p?=?0.003). Significant partial correlation was found for eveningness and sleep duration during weekdays (p?=?0.005), and not during weekends. Furthermore, evening orientation was associated with a reduced rested feeling on weekday mornings (p?<?0.001), but not on weekends. The most important sleep characteristic showing association with many cognitive and behavioral measures was the subjective feeling upon awakening—particularly during weekdays. Bootstrap mediation analyses demonstrated that sleep significantly mediated the effects of eveningness on behavioral problems, working memory, and sustained attention. Interestingly, mediation was only significant through the subjective feeling upon awakening on weekdays. The current findings indicate that the subjective feeling upon awakening is a much better predictor of daytime problems than subjective sleep quantity. Furthermore, the data suggest that negative outcomes in evening types are due to the fact that they wake up before their circadian drive for arousal and prior to complete dissipation of sleep pressure during weekdays. Interventions that target the misalignment of endogenous circadian rhythms and imposed rhythms are discussed. (Author correspondence: kbheijden@fsw.leidenuniv.nl)     

Chronotype preference matters for depression in youth

Morningness/eveningness (M/E) preference is an important circadian rhythm indicator with strong individual variation. M/E chronotype has been found to be correlated with depression in adults, yet the relationship is less clear in children and adolescents. Additionally, poor sleep quality is another commonly studied risk factor for depression. The aims of the present study are to investigate the independent effects of M/E chronotype on youth depression using both self-report and parental-report questionnaires. We also evaluated how poor sleep quality may affect the relationship through a mediating or moderating effect. In total, 2,139 students attending grades 1 to 7 participated in this study. They completed questionnaires regarding M/E chronotype, depression, and sleep quality. A total of 1,708 parents also participated and filled out parental-reports of emotional and behavioral problems of their children. The prevalence of self- and parental-report depression was 16.8% and 12.8% among young students, respectively. Overall, 15.4% of the students were the eveningness type. Being an eveningness type was independently associated with self-report depression after adjustment for poor sleep quality (OR = 1.86, 95% CI = 1.07–3.24). We also observed that poor sleep quality mediated the influence of M/E chronotype on self-report depression among students aged 7–13 years (p < 0.001). On the other hand, being an eveningness type was associated with a number of parental-report emotional and behavioral problems in the students, in addition to depression, although these associations become non-significant after adjusted for poor sleep quality. Our results demonstrate the importance of M/E chronotype on youth depression and poor sleep quality partly mediates this effect.     

Cognitive functioning of female nurses during the night shift: The impact of age,clock time,time awake and subjective sleepiness

ABSTRACT

Decline in cognitive functioning in the workplace is a major concern for health care systems. Understanding factors associated with nighttime functioning is imperative for instituting organizational risk management policies and developing personalized countermeasures. The present study aims to identify individual factors associated with cognitive functioning during the night shift of hospital nurses working on irregular rotating-shift schedules. Ninety-two female nurses were recruited from 17 wards in two general hospitals, using convenience sampling by clusters. Inclusion criteria were working at least 28 h a week (75% of full time) and one night shift per week. Exclusion criteria were pregnancy, diagnosed sleep disorders or medical conditions that may affect sleep and/or function. Cognitive performance was measured during the middle (03:00 h) and at the end (07:00 h) of the night shift using the Digit Symbol Substitution Task (DSST) and the Letter Cancellation Task (LCT) over two night shifts. Subjective sleepiness was assessed by the Karolinska Sleepiness Scale (KSS) at the same time points. All participants completed a sociodemographic questionnaire, the Munich ChronoType Questionnaire for Shift-Workers (MCTQShift) and the Pittsburgh Sleep Quality Index (PSQI). Sleep duration 24 h before the night shift and time awake since last sleep opportunity were monitored by actigraphy. Univariate repeated measures ANOVA found main effects for clock time (p<0.001), age (p<0.05), time awake (p<0.05) and sleepiness (p<0.01) for DSST correct responses; main effects for clock time (p<0.001) and sleepiness (p<0.001) for LCT capacity; and main effects for clock time (p<0.001) and age (p<0.01) for LCT omission errors. All factors remained significant in a mixed-model analysis for DSST. Cognitive performance among hospital nurses is low during the middle of the night shift and increases at the end of the shift; decreased functioning is associated with increased subjective sleepiness, older age and prolonged time awake. Identifying factors contributing to performance during the night shift may provide a basis for the development of risk management policies and preventative interventions.     

Sociodemographics of Pet Ownership among Adolescents in Great Britain: Findings from the HBSC Study in England,Scotland, and Wales

The aim of this study was to assess the prevalence of pet ownership among adolescents in Great Britain and identify any sociodemographic differences between pet owners and non-pet owners. A total of 14,328 11-to 15-year-old adolescents from England, Scotland, and Wales were included in the analysis. Results revealed 15-year-old adolescents were significantly more likely than 11-year-old adolescents to own dogs (OR = 1.146, p < 0.001) but less likely to own fish, reptiles, or amphibians (OR = 0.629, p < 0.001), and small mammals (OR = 0.630, p < 0.001). Thirteen-year-olds were significantly more likely than 11-year-olds to own dogs (OR = 1.240, p = 0.021) and birds (OR = 1.299, p = 0.010), but significantly less likely to own fish, reptiles, or amphibians (OR = 0.795, p < 0.001). No gender differences were found. White adolescents were more likely than non-white adolescents to own all pet types. Those living in single-parent families were significantly more likely than those living with two parents to own dogs (OR = 1.186, p = 0.013) and cats (OR = 1.319, p < 0.001). Furthermore, those who reported living in stepfamilies were also more likely to own cats (OR = 1.428, p < 0.001). Adolescents with siblings were more likely to own cats (OR = 1.391, p = 0.001), fish, reptiles, or amphibians (OR = 1.220, p = 0.037) than adolescents without siblings. Adolescents with employed parents (both or one) were significantly more likely than those with unemployed parents to own dogs (OR = 1.414, p = 0.002) and birds (OR = 1.523, p = 0.018). Adolescents from high-affluence families were less likely than adolescents from low-affluence families to own dogs (OR = 0.888, p = 0.037), small mammals (OR = 0.832, p = 0.005), and birds (OR = 0.801, p = 0.046). Furthermore, family affluence differences were found in different pet types. Differences in all pet types and siblings were also found in a proxy measure of attachment to pets. This study provides evidence that pet ownership is related to several sociodemographic factors. These are relevant to take into account when performing HAI studies on adolescents.     

Relationship of Neck Circumference to Cardiovascular Risk Factors

Objective: To determine a relationship between neck circumference (NC) and risk factors for coronary heart disease by evaluating the components of the metabolic syndrome. Research Methods and Procedures: The study group included 561 subjects (231 men and 330 women) who had no known major medical conditions and were not receiving any medication therapy. The subjects were those who attended a family health clinic for any reason between 1998 and December 2001. Main indicators studied included NC, waist circumference, waist‐to‐hip ratio, body mass index, blood pressure, and lipoprotein, glucose, and uric acid levels. Results: Pearson's correlation coefficients indicated a significant association between NC and body mass index (men, r = 0.71; women, r = 0.81; each, p < 0.0001), waist circumference (men, r = 0.75; women, r = 0.79; each, p < 0.0001), waist‐to‐hip ratio (men, r = 0.56; women, r = 0.63; each, p < 0.0001), total cholesterol (men, r = 0.50; women, r = 0.66; each, p < 0.0001), low‐density lipoprotein‐cholesterol (men, r = 0.42; women, r = 0.60; each, p < 0.0001), triglycerides (men, r = 0.48; women, r = 0.49; each, p < 0.0001), glucose (men, r = 0.21, p < 0.001; women, r = 0.44; p < 0.0001), uric acid (men, r = 0.50, p < 0.0001; women, r = 0.60, p < 0.001), and systolic (men, r = 0.53; women, r = 0.69; each, p < 0.0001), and diastolic (men, r = 0.55; women, r = 0.65; each, p < 0.0001) blood pressure. Discussion: Higher NC is correlated positively with the factors of the metabolic syndrome; therefore, it is likely to increase the risk of coronary heart disease.     

Individual differences in the sleep/wake cycle of Arctic flexitime workers

Daytime workers tend to have shorter sleep duration and earlier sleep onset during work days than on days off. Large individual differences in sleep onset and sleep duration may be observed on work days, but work usually synchronizes sleep offset to a similar time. The present study describes individual differences in sleep behaviour of 48 daytime workers (25 men, aged 20–58 years) from an iron ore mine in Northern Sweden. The aim of the study was to determine whether differences in sleep patterns during work days were associated with the outcomes of sleepiness and sleep complaints. Cluster analysis was used to group workers into two categories of sleep onset and sleep duration. The “Late Sleep Onset” cluster comprised workers who slept 1.30 h later than the “Early Sleep Onset” cluster (p < 0.0001 for all weekdays). The “Long Sleep Duration” cluster slept 1.10 h longer than the “Short Sleep Duration” cluster (p < 0.0002 for work nights). The “Late Sleep Onset” cluster reported less refreshing sleep (p < 0.01) and had lower sufficient sleep scores (p < 0.01) than the “Early Sleep Onset” cluster. The “Short Sleep Duration” cluster also reported lower scores for sufficient sleep (p < 0.04) than the “Long Sleep Duration” cluster. For combined characteristics (phase and duration), workers with a late phase and short sleep duration reported greater sleep debt and sleepiness than workers with an early phase and short sleep duration (p < 0.02). Work schedule and commuting time modulate both sleep phase and sleep duration independently. Workers, classified as having an intermediate sleep phase preference, can organize their sleep time in order to minimize sleep debt and sleepiness symptoms. Individual differences in sleep phase and duration should be considered when promoting well-being at work even among groups with similar sleep needs. In order to minimize sleep debt and sleepiness symptoms, successful sleep behaviour could be promoted involving extend use of flexitime arrangement (i.e. later starting times) and reduce use of alarm clocks.     

Association between depressive symptoms and morningness-eveningness,sleep duration and rotating shift work in Japanese nurses

Higher depressive symptoms have been reported in rotating shift workers compared with day workers. Depressive symptoms in adults who do not engage in night work have also been shown to be associated with chronotype and sleep duration. This study examines associations between depressive symptoms, morningness-eveningness (i.e. the degree to which people prefer to be active in the morning or the evening), sleep duration and rotating shift work. Japanese nurses (1252 day workers and 1780 rotating shift workers, aged 20–59) were studied using a self-administered questionnaire. The questionnaire covered depressive symptoms, morningness-eveningness, sleep habits and demographic characteristics of the participants. The Center for Epidemiologic Studies Depression Scale (CES-D) was used to determine the levels of depressive symptoms. A Japanese version of the Morningness-Eveningness Questionnaire (MEQ) was used to measure morningness-eveningness. The CES-D score of shift workers was significantly (p < 0.05) higher than that of day workers. The MEQ score was significantly (p < 0.05) lower (i.e. greater eveningness) in shift workers than in day workers. Sleep duration on the day shift was significantly (p < 0.05) shorter in shift workers than in day workers. Simple linear regression revealed that the MEQ score, sleep duration on the day shift and current work shift (i.e. rotating shift work) were significantly (p < 0.05) associated with the CES-D score. Multivariate linear regression indicated that greater eveningness and shorter sleep duration were independently associated with higher CES-D scores, while rotating shift work was not. These associations between the MEQ score, the sleep duration and the CES-D score were also confirmed in both day workers and shift workers when the groups were analyzed separately. These results suggest that greater eveningness and shorter sleep duration on the day shift were independently associated with higher levels of depressive symptoms, which may explain associations between rotating shift workers and depressive symptoms. These findings have important implications for the development of novel strategies for preventing poor mental health in day workers and rotating shift workers.     

Bullying,sleep/wake patterns and subjective sleep disorders: Findings from a cross-sectional survey

The aim of this study was to explore: (a) sleep patterns and disorders possibly associated with adolescent bullying profiles (pure bully, pure victim, bully/victim and neutral) and (b) the effect of sleep on psychosocial problems (externalized and internalized) related to bullying. The sample consisted of 1422 students aged 10–18 (mean?=?14.3, SD?=?2.7; 57% male) from five socioeconomically diverse schools in France. Bullying profiles were obtained using the revised Bully–Victim Questionnaire. Subjective sleep disorders were assessed using the Athens Insomnia Scale. School-week and weekend sleep/wake patterns were recorded. Internalizing problems were investigated using a Perceived Social Disintegration Scale and a Psychological Distress Scale. Externalizing behaviors were assessed using a General Aggressiveness Scale and an Antisocial Behavior Scale. These questionnaires were administered during individual interviews at school. After controlling for effects of gender and age, victims of bullying showed significantly more subjective sleep disturbances than the pure-bully or neutral groups (p?<?0.001). Bullies’ sleep schedules were more irregular (p?<?0.001 for bedtime irregularity and p<0.01 for wake-up time irregularity) and their sleep duration was shorter than their schoolmates (p?<?0.001 for the school week and p?<?0.05 for the weekend). There was an effect of sleep on psychosocial problems related to bullying, and our results indicate that sleep has a moderating effect on aggression in bullies (p?<?0.001). This would suggest a higher vulnerability of bullies to sleep deprivation. These results show differences in sleep problems and patterns in school-bullying profiles. Findings of this study open up new perspectives for understanding and preventing bullying in schools, with implications for research and clinical applications.     

Major Increase in Prevalence of Overweight and Obesity between 1987 and 2001 among Danish Adults

Objective: The aim of the study was to examine the secular trends in the prevalence of obesity (BMI ≥ 30.0 kg/m²) and overweight (25.0 ≤ BMI < 30.0 kg/m²) in Danish adults between 1987 and 2001. Research Methods and Procedures: The study included self‐reported weight and height of 10, 094 men and 9897 women 16 to 98 years old, collected in a series of seven independent cross‐sectional surveys. Prevalence and changes in prevalence of obesity and overweight stratified by sex and age groups were determined Results: The prevalence of obesity more than doubled between 1987 and 2001, in men from 5.6% to 11.8% [odds ratio (OR) = 2.3, 95% confidence interval (CI) = 1.9 to 2.8, p < 0.0001] and in women from 5.4% to 12.5% (OR = 2.6, 95% CI = 2.1 to 3.2, p < 0.0001), with the largest increase among the 16‐ to 29‐year‐old subjects (men, from 0.8% to 7.5%, OR = 10.2, 95% CI = 4.1 to 25.3, p < 0.0001; women, from 1.4% to 9.0% OR = 7.0, 95% CI = 3.5 to 14.1, p < 0.0001). Between 1987 and 2001, the prevalence of overweight increased from 34% to 40% in men and from 17% to 27% in women. Discussion: The prevalence of overweight and obesity in Denmark has increased substantially between 1987 and 2001, particularly among young adults, a development that resembles that of other countries. There is clearly a need for early preventive efforts in childhood to limit the number of obesity‐related complications in young adults.     

Associations between chronotype,morbidity and mortality in the UK Biobank cohort

Later chronotype (i.e. evening preference) and later timing of sleep have been associated with greater morbidity, including higher rates of metabolic dysfunction and cardiovascular disease (CVD). However, no one has examined whether chronotype is associated with mortality risk to date. Our objective was to test the hypothesis that being an evening type is associated with increased mortality in a large cohort study, the UK Biobank. Our analysis included 433 268 adults aged 38–73 at the time of enrolment and an average 6.5-year follow-up. The primary exposure was chronotype, as assessed through a single self-reported question-defining participants as definite morning types, moderate morning types, moderate evening types or definite evening types. The primary outcomes were all-cause mortality and mortality due to CVD. Prevalent disease was also compared among the chronotype groups. Analyses were adjusted for age, sex, ethnicity, smoking, body mass index, sleep duration, socioeconomic status and comorbidities. Greater eveningness, particularly being a definite evening type, was significantly associated with a higher prevalence of all comorbidities. Comparing definite evening type to definite morning type, the associations were strongest for psychological disorders (OR 1.94, 95% CI 1.86–2.02, p = < 0.001), followed by diabetes (OR 1.30, 95% CI 1.24–1.36, p = < 0.001), neurological disorders (OR 1.25, 95% CI 1.20–1.30, p = < 0.001), gastrointestinal/abdominal disorders (OR 1.23, 95% CI 1.19–1.27, p = < 0.001) and respiratory disorders (OR 1.22, 95% CI 1.18–1.26, p = < 0.001). The total number of deaths was 10 534, out of which 2127 were due to CVD. Greater eveningness, based on chronotype as an ordinal variable, was associated with a small increased risk of all-cause mortality (HR 1.02, 95% CI 1.004–1.05, p = 0.017) and CVD mortality (HR 1.04, 95% CI 1.00–1.09, p = 0.06). Compared to definite morning types, definite evening types had significantly increased risk of all-cause mortality (HR 1.10, 95% CI 1.02–1.18, p = 0.012). This first report of increased mortality in evening types is consistent with previous reports of increased levels of cardiometabolic risk factors in this group. Mortality risk in evening types may be due to behavioural, psychological and physiological risk factors, many of which may be attributable to chronic misalignment between internal physiological timing and externally imposed timing of work and social activities. These findings suggest the need for researching possible interventions aimed at either modifying circadian rhythms in individuals or at allowing evening types greater working hour flexibility.     

Factors differentiating infants identified by parents as problem sleepers,and those that are not

Sleep problems are common during infancy. Possible factors which contribute to parental perception of problem sleep were investigated as part of a pilot study collecting objective data on the sleep of 1-year-old New Zealand infants (n = 52 families). Sleep of each infant was monitored for a week at home (ankle actigraphy and sleep diaries, which also included daily infant mood ratings) and parents completed questionnaires addressing their infant’s sleep, the living and sleeping environment, and feeding. Thirty-five percent of the infants were considered by parents to have a sleeping problem. These infants had shorter night-time sleep as measured by actigraphy (median = 10.0 h vs 10.7 h for non-problem sleepers [U = 193.0, P < 0.05]), less total sleep per 24 h (median = 11.4 h vs 12.5 h [U = 169.5, P < 0.01]), and were put to bed more often per 24 h (median = 3.5 times vs 3.0 times [U = 201.5, P< 0.05]). Problem sleepers were also more likely to spend > 20 min awake at night (68% vs 32% [c2 = 16.78, P < 0.001]), as well as currently being breastfed (55% vs 45% [c2 = 5.97, P < 0.05]), and to have moderate-bad mood at bedtime (59% vs 41% [c2 = 6.54, P< 0.05]). Sleep was also related to parent’s diary ratings of their infant’s mood and temperament. This study highlights factors contributing to parental perception of problem sleep which is vital for recognizing and managing such problems throughout infancy.