Impact of a physical activity intervention on adolescents' subjective sleep quality: a pilot study.

BACKGROUND: The aim of this pilot study was to examine the impact of a brief physical activity intervention on adolescents' subjective sleep quality. Cross-sectional studies indicate that physically active adolescents have better subjective sleep quality than those with more sedentary habits. However, less is known about the effectiveness of physical activity interventions in improving adolescents' subjective sleep quality. METHODS: In a three-week physical activity intervention, four Icelandic upper secondary schools were randomized to either an intervention group with pedometers and step diaries or a control group without pedometers and diaries. Out of 84, a total of 53 students, aged 15-16 years, provided complete data or a minimum of two days step data (out of three possible) as well as sleep quality measures at baseline and follow-up. Subjective sleep quality, the primary outcome in this study, was assessed with four individual items: sleep onset latency, nightly awakenings, general sleep quality, and sleep sufficiency. Daily steps were assessed with Yamax CW-701 pedometers. RESULTS: The intervention group ( n = 26) had significantly higher average step-count ( p = 0.03, partial η2 = 0.093) compared to the control group ( n = 27) at follow-up. Subjective sleep quality improved ( p = 0.02, partial η2 = 0.203) over time in the intervention group but not in the control group. CONCLUSIONS: Brief physical activity interventions based on pedometers and step diaries may be effective in improving adolescents' subjective sleep quality. This has important public health relevance as the intervention can easily be disseminated and incorporated into school curricula.

Electronic screen use and selected somatic symptoms in 10-12 year old children.

OBJECTIVE: Screen-based media use by children and adolescents has increased in recent years but the consequences of their use are not well understood. The objective of this study was to provide a comprehensive examination of the relationship between screen-based activities and a selection of single and multiple self-reported somatic symptoms in a large sample of 10-12 year old children. METHOD: We use data from the population-based 2011 Youth in Iceland school survey (N=10,829, response rate: 84.5%, boys: 49.9%) that is conducted triennially in 5th-7th grades in all secondary schools in Iceland. Self-reported measures of common screen-based activities were hypothesized to predict the odds of dizziness, tremors, headaches, stomach aches, and multiple symptoms. RESULTS: In general the reported prevalence of symptoms increased with greater number of hours reported on screen based activity for boys and girls. This held for all individual screen activities as well as the cumulative measure of daily minutes spent on screen-based media and prevalence of one or more somatic symptoms. CONCLUSIONS: This study confirms previous findings and puts forth additional information concerning the relationship between the prevalence of electronic screen use and somatic symptoms in 10-12 year old children.