A pilot cluster-randomised study to increase sleep duration by decreasing electronic media use at night and caffeine consumption in adolescents.

OBJECTIVE: Bedtime electronic media use and caffeine consumption are risk factors for insufficient sleep and poor sleep quality during adolescence, which are in turn risk factors for mental wellbeing. Our study tested the effectiveness of a brief school-based psychoeducative intervention to primarily increase sleep duration, by decreasing bedtime electronic media use and caffeine consumption. Secondary outcomes included improving sleep quality and difficulties, daytime tiredness, and mental wellbeing. METHOD: A pilot cluster-randomised controlled study was conducted involving a 25-min psychoeducative school-based intervention combined with parent information. 352 adolescents from seven schools participated (Intervention Group/IG = 192 students vs. Control Group/CG = 160 students; age: Mean = 15.09 years; SD = 1.65 years; Females = 163). The intervention included information on the importance of sleep and good sleep hygiene habits, particularly emphasizing behavioural rules of avoiding electronic media use at night and evening-time caffeine consumption. A leaflet containing the rules was also sent to parents of IG participants. Baseline and post-intervention sessions were held approximately four weeks apart. RESULTS: Multilevel analyses revealed a significant but modest decrease in electronic media use for participants in the IG versus CG, but showed no effect on caffeine consumption or sleep duration. Moreover, the intervention did not impact any secondary outcome. CONCLUSIONS: Findings indicate the potential effectiveness of a short and easily administrable intervention to decrease electronic media use at night, which may be incorporated into school curricula and standardised for wider use in primary prevention. However, no further benefits of the intervention were found.

Salivary and hair glucocorticoids and sleep in very preterm children during school age.

Very preterm birth involves increased stress for the child, which may lead to programming of the hypothalamic-pituitary-adrenal (HPA) axis activity and poor sleep in later life. Moreover, there is evidence for a relationship between HPA axis activity and sleep. However, research with objective sleep measures in very preterm children during school-age is rare. Eighty-five healthy children born very preterm (<32nd gestational week) and 91 full-term children aged 7-12 years were recruited for the present study. To assess HPA axis activity, salivary cortisol was measured at awakening, 10, 20, and 30min later. In addition, hair cortisol and cortisone concentrations were quantified using liquid chromatography tandem mass spectrometry to assess cumulative endocrine activity over the preceding months. One night of in-home polysomnographic sleep assessment was conducted to assess sleep duration, sleep continuity, and sleep architecture. Children born very preterm showed significantly lower levels of cortisol at awakening and lower overall post-awakening cortisol secretion, lower cortisone in hair, and earlier sleep onset than full-term children. Across the whole sample, overall post-awakening cortisol secretion was positively related to sleep onset time and negatively to sleep duration. The association between prematurity status and post-awakening cortisol secretion was partially mediated by earlier sleep onset time. In conclusion, this study provides evidence for a possible down-regulation of the HPA axis activity and slightly earlier sleep phase in very preterm children during school age.

Gait in Very Preterm School-Aged Children in Dual-Task Paradigms.

OBJECTIVE: The control of gait requires executive and attentional functions. As preterm children show executive and attentional deficits compared to full-term children, performing concurrent tasks that impose additional cognitive load may lead to poorer walking performance in preterm compared to full-term children. Knowledge regarding gait in preterm children after early childhood is scarce. We examined straight walking and if it is more affected in very preterm than in full-term children in dual-task paradigms. STUDY DESIGN: Twenty preterm children with very low birth-weight (≤ 1500 g), 24 preterm children with birth-weight > 1500 g, and 44 full-term children, born between 2001 and 2006, were investigated. Gait was assessed using an electronic walkway system (GAITRite) while walking without a concurrent task (single-task) and while performing one concurrent (dual-task) or two concurrent (triple-task) tasks. Spatio-temporal gait parameters (gait velocity, cadence, stride length, single support time, double support time), normalized gait parameters (normalized velocity, normalized cadence, normalized stride length) and gait variability parameters (stride velocity variability, stride length variability) were analyzed. RESULTS: In dual- and triple-task conditions children showed decreased gait velocity, cadence, stride length, as well as increased single support time, double support time and gait variability compared to single-task walking. Further, results showed systematic decreases in stride velocity variability from preterm children with very low birth weight (≤ 1500 g) to preterm children with birth weight > 1500 g to full-term children. There were no significant interactions between walking conditions and prematurity status. CONCLUSIONS: Dual and triple tasking affects gait of preterm and full-term children, confirming previous results that walking requires executive and attentional functions. Birth-weight dependent systematic changes in stride velocity variability indicate poorer walking performance in preterm children who were less mature at birth.

Intraindividual long-term stability of sleep electroencephalography in school-aged children.

OBJECTIVE: To examine the long-term stability of sleep duration, sleep continuity, and sleep architecture assessed via unattended home sleep electroencephalography (EEG) during middle childhood. METHODS: A total of 69 healthy children (18 girls and 51 boys) aged 8.2 years (standard deviation = 1.3 years) at T1 underwent unattended home sleep EEG on two nights separated by 18.5 months (standard deviation = 3.9 months). Of the children, 34 (49.3%) children were born prematurely (<32 gestational weeks; mean birth weight = 1367 g) and 35 (50.7%) children were born at term (mean birth weight = 3275 g). RESULTS: We found moderate to substantial stability (all p <0.001) for total sleep time (TST; intraclass correlation coefficient [ICC] = 0.65), slow wave sleep (SWS; min, %: ICC = 0.49), and stage 2 sleep (min; ICC = 0.47), and found fair stability (all p <0.013) for sleep efficiency (ICC = 0.28), nocturnal awakenings (ICC = 0.33), stage 2 sleep (%; ICC = 0.32), and rapid eye movement (REM) sleep (min: ICC = 0.33; %: ICC = 0.27). Prematurity status was not associated with stability of sleep EEG indices over time. CONCLUSIONS: Long-term follow-up of one night of unattended home sleep EEG during middle childhood reveals that TST, stage 2 sleep, and SWS are relatively stable, trait-like characteristics. This applies less strongly for sleep efficiency, nocturnal awakenings, and REM sleep. Stage 1 sleep and REM latency showed no stability.

Morning cortisol secretion in school-age children is related to the sleep pattern of the preceding night.

Sleep disturbance in childhood is common and a risk factor for poor mental health. Evidence indicates that disturbed sleep is associated with altered hypothalamic-pituitary-adrenal axis (HPAA) activity. Knowledge regarding the association between HPAA-activity and objective sleep measures particularly regarding sleep architecture in school-age children is missing. Sleep-electroencephalography was administered to 113 children aged 6-10 years (including 58 children born very preterm and 55 born at term) during one night at the children's homes and sleep duration, sleep continuity, and sleep architecture were assessed. To assess the cortisol awakening response at the following morning, cortisol secretion was measured at awakening, 10, 20, and 30min later. Regression analyses controlling child age, gender, prematurity status, and the awakening time revealed that morning cortisol secretion was negatively associated with sleep duration and slow wave sleep and positively associated with the relative amount of Stage 2 sleep during the preceding night. In addition, morning cortisol secretion linearly increased with age. In conclusion, associations of sleep disturbance with poor mental health may be confounded with altered HPAA-activity.

The role of sleep and the hypothalamic-pituitary-adrenal axis for behavioral and emotional problems in very preterm children during middle childhood.

Very preterm children are at higher risk to develop behavioral and emotional problems, poor sleep, and altered hypothalamic-pituitary-adrenocortical activity (HPAA). However, knowledge on objective sleep and HPAA as well as their role for the development of behavioral and emotional problems in very preterm children is limited. Fifty-eight very preterm children (<32nd gestational week) and 55 full-term children aged 6-10 years underwent one night of in-home polysomnographic sleep assessment. HPAA was assessed with four saliva samples in the morning (morning cortisol secretion) and four saliva samples in the evening (evening cortisol secretion). Parents completed the Strengths and Difficulties Questionnaire (SDQ) to assess children's behavioral and emotional problems and a subscale of the Children's Sleep Habits Questionnaire to assess sleep disordered breathing. Very preterm children showed more behavioral and emotional problems (SDQ total behavioral/emotional difficulties, emotional symptoms), poorer sleep (more nocturnal awakenings, more stage 2 sleep, less slow wave sleep), and faster decreasing evening cortisol secretion compared to full-term children. Across the whole sample, more stage 2 sleep and/or less slow wave sleep were associated with more SDQ total behavioral/emotional difficulties, hyperactivity-inattention, and peer problems. Lower morning cortisol secretion and lower evening cortisol secretion were associated with more conduct problems. In very preterm children, increased SDQ total behavioral/emotional difficulties was partially explained by less restorative sleep including more stage 2 sleep and less slow wave sleep. This result points to the importance of restorative sleep for the behavioral and emotional development of very preterm children during middle childhood.

Adolescents' electronic media use at night, sleep disturbance, and depressive symptoms in the smartphone age.

Adolescence is a time of increasing vulnerability for poor mental health, including depression. Sleep disturbance is an important risk factor for the development of depression during adolescence. Excessive electronic media use at night is a risk factor for both adolescents' sleep disturbance and depression. To better understand the interplay between sleep, depressive symptoms, and electronic media use at night, this study examined changes in adolescents' electronic media use at night and sleep associated with smartphone ownership. Also examined was whether sleep disturbance mediated the relationship between electronic media use at night and depressive symptoms. 362 adolescents (12-17 year olds, M = 14.8, SD = 1.3; 44.8% female) were included and completed questionnaires assessing sleep disturbance (short sleep duration and sleep difficulties) and depressive symptoms. Further, participants reported on their electronic media use in bed before sleep such as frequency of watching TV or movies, playing video games, talking or text messaging on the mobile phone, and spending time online. Smartphone ownership was related to more electronic media use in bed before sleep, particularly calling/sending messages and spending time online compared to adolescents with a conventional mobile phone. Smartphone ownership was also related to later bedtimes while it was unrelated to sleep disturbance and symptoms of depression. Sleep disturbance partially mediated the relationship between electronic media use in bed before sleep and symptoms of depression. Electronic media use was negatively related with sleep duration and positively with sleep difficulties, which in turn were related to depressive symptoms. Sleep difficulties were the more important mediator than sleep duration. The results of this study suggest that adolescents might benefit from education regarding sleep hygiene and the risks of electronic media use at night.

In school-age children who were born very preterm sleep efficiency is associated with cognitive function.

AIMS: This study examined whether the association between sleep duration, as well as sleep continuity, and cognitive function differs between normally developing preterm children compared to full-term children during middle childhood. METHODS: A total of 58 early preterm (<32 weeks' gestation) and 55 full-term children, aged 6-10 years and enrolled in elementary school, were assessed on sleep duration, sleep continuity and cognitive function. We used in-home polysomnographic recordings of total sleep time, sleep efficiency and nocturnal awakenings. Cognitive tests included intelligence, arithmetic, selective attention, verbal memory, and visuospatial memory. RESULTS: Preterm children showed poorer performance in intelligence, arithmetic, selective attention, and visuospatial memory (d = 0.38-0.79, p < 0.05) and more objectively assessed nocturnal awakenings (d = 0.40, p = 0.03) than full-term children. Associations of sleep efficiency and cognitive functions (intelligence, arithmetic, selective attention, visuospatial memory) were positive and stronger for preterm children (ß = 0.17-0.31, p < 0.05), while they were nonsignificant for full-term children. CONCLUSION: Results confirm lower cognitive test scores and more nocturnal awakenings in normally developing early preterm children compared to full-term children. Furthermore, poor sleep efficiency may aggravate cognitive deficits, particularly in children who are more vulnerable due to premature birth.

Sleep duration, positive attitude toward life, and academic achievement: the role of daytime tiredness, behavioral persistence, and school start times.

Sleep timing undergoes profound changes during adolescence, often resulting in inadequate sleep duration. The present study examines the relationship of sleep duration with positive attitude toward life and academic achievement in a sample of 2716 adolescents in Switzerland (mean age: 15.4 years, SD = 0.8), and whether this relationship is mediated by increased daytime tiredness and lower self-discipline/behavioral persistence. Further, we address the question whether adolescents who start school modestly later (20 min; n = 343) receive more sleep and report better functioning. Sleeping less than an average of 8 h per night was related to more tiredness, inferior behavioral persistence, less positive attitude toward life, and lower school grades, as compared to longer sleep duration. Daytime tiredness and behavioral persistence mediated the relationship between short sleep duration and positive attitude toward life and school grades. Students who started school 20 min later received reliably more sleep and reported less tiredness.