Pre-bedtime activities and light-emitting screen use in university students and their relationships with self-reported sleep duration and quality

In a three-day field study among 61 university students, we collected data on self-reported light-emitting screen activities (watching TV/series and using social media) and other behaviours (physical activity and food intake) during the 2 hours before bedtime and examined interrelations with self-reported sleep duration and quality. Students spent on average 19 minutes on screens using social media and 29 minutes watching TV/series before going to bed. Linear mixed model analyses revealed that a 10-minute increase in pre-bedtime social media use was associated with a significant decrease in sleep duration of 7 minutes, while 10 extra minutes of watching TV/series tended to increase sleep duration by 3 minutes. Physical activity and food intake before bedtime, and total screen time in bed were not significantly related to sleep duration. Subjective sleep quality was not significantly correlated with any of the investigated pre-sleep activities. In line with previous research, these findings suggest that the influence of pre-bedtime light-emitting screen use on sleep duration might be (partly) attributable to differences in screen activities. Discriminating between various types of screen activities is important when researching and developing recommendations for pre-bedtime behavioural strategies that are supportive for sleep, (school) performance and health.