Daytime sleepiness and associated factors in Japanese school children.

OBJECTIVE

To examine daytime sleepiness and sleepiness interrelationship with sleep-wake patterns, eating habits, physical activity, and TV/video game time.

STUDY

DESIGN

A cross-sectional survey with 9,261 school children (mean age of 12.8 years) from 93 junior high schools in Toyama prefecture, Japan.

RESULTS

The main outcome measures were daytime sleepiness during schooldays and sleepiness interrelationship with sleep-wake patterns, eating habits, physical activity, and visual media use. A total of 2,328 children (25.2%) reported sleepiness almost always and 4,401 (47.6%) sleepiness often. Regarding sex difference, a higher proportion of girls reported sleepiness in comparison to boys (79% vs 66%, P < .001). Higher body mass index values were associated with the presence of sleepiness. In girls with preferences for daily snack (versus those who reported no snack) sleepiness presented significantly (P < .001) higher values. Reduced sleep time was significantly associated with sleepiness. The prevalence of sleepiness did not significantly differ among groups who had 7.5 hours sleep or more. A dose-response relation was found between sleepiness and sleep disturbances, physical activity, and media use time.

CONCLUSIONS

Sleep insufficiency represents a main cause for daytime sleepiness in Japanese junior high school children. Proper sleep habits, high physical activity level, and limited TV viewing time should be promoted among school children.