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Objectives The causal nature of the sleep-obesity association is unclear. To control for potential confounding by genes and shared environment, we studied monozygotic twin pairs discordant for body mass index (BMI). First, we investigated sleep in relation to BMI. Second, we examined associations of objective and subjective sleep duration and sleep debt (objective or subjective sleep duration minus subjective sleep need) with eating behaviors and physical activity (PA). Design Cross-sectional study. Setting Finnish twins in everyday life circumstances. Participants Seventy-four healthy young adult monozygotic twin pairs, of whom 36 were BMI-discordant (∆BMI ≥ 3 kg/m2). Measurements Clinical measurements estimated BMI and body composition. Sleep, eating, and PA behaviors were measured by self-report and actigraphy. Results Compared to co-twins with lower BMI, co-twins with higher BMI reported shorter sleep (P = .043), more snoring (P = .0093), and greater tiredness (P = .0013) and trended toward eveningness (P = .036). Actigraphy-measured sleep duration correlated highly within BMI-discordant twin pairs (r = 0.63, P = .004). Subjective sleep debt was consistently positively associated with disinhibited eating and binge eating, but not with BMI. Subjective and objective sleep debt had negative correlations with moderate-to-vigorous PA. Conclusions Twins with higher BMI showed less favorable sleep characteristics than their co-twins with lower BMI. Subjective sleep debt is a potential target for intervention to reduce eating and PA behaviors that promote weight gain. Experimental studies could elucidate mechanisms underlying tiredness in individuals with higher BMI and investigate causal relationships between sleep debt, BMI, and lifestyle.

Temperament and sleep in infants are related but also distinct concepts. The longitudinal effects of temperament on sleep in infancy remain unclear, although this information is potentially important for the prevention and treatment of early sleep problems. We examined how various temperament features influence sleep development during the first year of life in a large birth cohort. This study comprised mother-infant dyads with complete longitudinal data on sleep, temperament and sociodemographic measurements at six and 12 months (N = 1436). We observed that higher infant Negative Affectivity was related to several sleep problems, and that many subscales of Negative Affectivity and Orienting/Regulation predicted worse sleep and deterioration in sleep problems from six to 12 months. Few associations between Surgency and sleep were found. Our findings highlight especially Negative Affectivity as a risk factor for persistent and increasing sleep problems, and also the specific importance of the fine-grained aspects of temperament in predicting infant sleep development.

Objective The present study examined how sleep duration and sleep quality are associated with cognitive performance in 8-year-old children using standardized neurocognitive tests. Methods Two hundred ninety children aged 7.4–8.8years participated in the study. Sleep duration and quality were measured using actigraphs and the Sleep Disturbance Scale for Parents. Cognitive performance was measured using four subtests of the Wechsler Intelligence Scale for Children III, the Beery Developmental Test of Visual-Motor Integration (VMI), and the Narrative memory subtest of the Developmental Neuropsychological Assessment for Children. Results When adjusting for age, sex, and maternal education, shorter sleep duration, but not sleep quality, was associated with lower visuospatial abilities ( p -values ⩽0.043). Sleep duration and quality were not associated with verbal abilities ( p -values⩾0.18). With regard to the individual test results, shorter sleep duration was associated with worse performance in Visual-Motor Integration ( p =0.028), and when excluding children with high depression scores the same was also true with Block Design ( p -values⩽0.047). Moreover, poor sleep efficiency was associated with worse performance in Similarities ( p =0.004). Conclusions In a community sample of 8-year-old children, those who slept less or had poorer sleep quality had lower test scores in cognitive tasks, particularly those pertaining to visuospatial performance, although the association was not very strong.

To study the associations between sleep quality/quantity and performance in auditory/visual working memory tasks of different load levels.Sixty schoolchildren aged 6 to 13 years from normal school classes voluntarily participated. Actigraphy measurement was done during a typical school week for 72 consecutive hours. It was timed together with the working memory experiments to obtain information on children's sleep during that period. The n-back task paradigm was used to examine auditory and visual working memory functions.Lower sleep efficiency and longer sleep latency were associated with a higher percentage of incorrect responses in working memory tasks at all memory load levels (partial correlations, controlling for age, all p values.05, except in visual 0-back and auditive 2-back tasks); shorter sleep duration was associated with performing tasks at the highest load level only (partial correlations, controlling for age,p.05). Also in general linear models (controlling for age, gender, and socioeconomic status), sleep efficiency (F = 11.706, p = .050) and latency (F = 3.588, p = .034) were significantly associated with the mean incorrect response rate in auditory working memory tasks.Sleep quality and quantity affect performance of working memory tasks in school-age children. In children with learning difficulties the possibility of underlying sleep problems should be excluded.

Objective To assess associations between the quantity and quality of children's sleep and parent- and teacher-reported psychiatric symptoms. Method Forty-nine physically healthy 7- to 12-year-old children from normal classes participated. They were monitored for 72 consecutive hours with belt-worn activity monitors (actigraphs) to obtain objective data on their daytime and nighttime activity and sleep. In addition, Child Behavior Checklists and Teacher's Report Forms were filled out by the parents and teachers, respectively. Results Quantity of sleep was significantly associated with total symptom score on the Teacher's Report Form. The highest associations were found between low true sleep time and teacher-reported externalizing symptoms such as aggressive and delinquent behavior and attention and social problems. Sleep parameters were not associated with parent-reported psychiatric symptoms, except for the association found between delayed sleep latency and aggressive, delinquent behavior. Conclusions The objectively measured amount of school-age children's sleep was associated with teacher-reported psychiatric symptoms. Parents may be unaware of their child's sleep deficiencies as the behavioral problems may be more evident at school than at home. Sensitive and objective measurements are needed to rule out the possibility of inadequate sleep underlying behavioral problems.