Bedtime and its correlates among secondary school children in Karachi, Pakistan.

Objectives: To determine the demographic and lifestyle predictors of bedtime among secondary school children in Karachi, Pakistan, and to assess what variables of daytime functioning correlate with bedtimes.

Methods: The cross-sectional study was conducted between September and October 2007, among secondary school students aged 10-16 years, in the socio-economically diverse city of Karachi. Data was collected using a pre-tested self-reporting questionnaire, and analysed by univariate and multivariate logistic regression analysis on SPSS version 15. A p value of <0.05 was considered significant. All odds ratio were recorded with a 95% confidence interval.

Results: Of the 539 students in the study, 102 (18.92%) were male and 437 (81.07%) were female. Of the total, 401 (74.4%) slept late (after 10pm). Homework and TV shows were more frequent reasons of bedtime among the late-sleepers, whereas parental influence was reported more by the early-sleepers. Advancing grade at school, father's profession as doctor or engineer and sleeping alone in the room were independent predictors of late bedtime on multivariate analysis (p<0.05). Students who were older, did not share a bed, or slept for >3 hours during the afternoon, were more likely to sleep after 10pm on univariate analysis only (p<0.05). Students sleeping late were more likely to get less daily and nocturnal sleep, wake-up later, require multiple wake up reminders in the morning, fall asleep in a morning class and feel tired during the day (p<0.05). They were also 2.42 times less likely to feel that they got adequate sleep to be fresh in the morning (p<0.001; 95% CI 1.58-3.72).

Conclusion: More than three-fourth of our secondary school children sleep late. Parents and teachers should foster healthy sleeping habits and early bedtimes among students to allow optimal daytime functioning.