Waking Activities and Sleep: Analysis of United Kingdom Adolescents' Daily Time-Use Diaries

Purpose: To investigate waking activities associated with risks of short and long sleep in a representative cohort of UK adolescents.

Methods: Data from 14-year-olds participating in the UK Millennium Cohort Study were used. Daily time-use diaries were completed by adolescents on two randomly selected days (one weekday and one weekend) to capture their activities within a 24-hour period from 4 a.m. of each selected day. Short and long sleep duration categories were defined as beyond the extreme lower and upper thresholds of acceptable age-specific sleep durations recommended by the National Sleep Foundation, respectively.

Results: Approximately 8% and 6% were short sleepers on weekdays and weekends, respectively. On average, adolescents spent 33% of their time awake per weekend day on recreational digital media activities. Compared with those who had optimal sleep on weekdays, short sleepers spent more time on personal care (mean difference = +56 minutes; 95% confidence interval [CI]: 21; 92) and less time on exercise activities (mean difference = -15 minutes; 95% CI: -27; -3). Ten-minute increase in daily digital media activity was associated with 2% (95% CI: 1.01; 1.03) higher relative risk of adolescents being short sleepers on weekdays. Relative risk of short sleeping was 1.03 (95% CI: 1.01; 1.04) times higher for every10-minute daily increase in travel time on weekdays.

Conclusions: Adolescents spend up to one-third of their time awake per day on digital media. However, more time spent on personal care and travel on weekdays and weekends is associated with increased risk of short sleep. These findings permit a reflection on appropriate interventions needed to improve sleep duration in sleep-deprived teens.