Bedtimes and family size in English schoolchildren.

Data from a survey of 3727 14-year-old children from 31 secondary schools in England in 1984-85 were analysed to obtain information about bedtimes and sleep duration in relation to the number of children in the family. Subjects completed a questionnaire, anonymously, in class. The modal bedtime was 22 30 and the modal time spent in bed was 9 h. Males went to bed later than females (P less than 0.05) but there was no significant difference between the sexes in the time they spent in bed. As the number of siblings increased bedtimes became later (P less than 0.05) and the time spent in bed markedly decreased (P less than 0.001). These results suggest that young adolescents from large families (4 or more children) may be more at risk from inadequate sleep than those in smaller families.