Prebed Screen Use, Activity, and Food in Relation to Sleep in Youth: A Repeated Measures Study

Abstract

OBJECTIVES: To assess screen use, physical activity, and self-reported food intake in the hour before bed in youth and explore relationships with sleep. METHODS: Screen use and moderate-to-vigorous physical activity were captured using wearable cameras over 4 nights in 83 youth (37% indigenous M¯ aori, 42% women) aged 11 to 14.9 years. Food/beverage intake was measured via 3 24-hour diet recalls, and sleep was measured using Axivity accelerometers (8 nights). Associations were estimated using a repeated measure analysis with mixed effects regression models using sleep variables as the outcome, prebed behaviors as the exposure, and participant as a random effect. RESULTS: 99% of participants used screens on 83% of nights, for a median of 32 minutes (IQR 23-40). Screen use did not significantly impact total sleep time (mean difference; 95% CI, 16 minutes, −7 to 38) or other sleep outcomes but did extend sleep latency by 84% (equivalent to 23.1 minutes). A total of 22% of participants undertook moderate-to-vigorous physical activity on 7% of nights, with a median duration of 2.3 minutes (IQR, 0.9-14.4); on these nights, youth received 34 minutes (95% CI, 0-67) more sleep. Almost two-thirds of youth consumed food before bed (30.7% of nights), with a median energy intake of 1465 kJ (IQR, 713-2134). No significant associations were observed between any dietary variables and any sleep outcome. CONCLUSIONS: Few youth adhere to current prebed sleep guidelines aiming to restrict screen use, physical activity, and food intake, and these behaviors have little detrimental association with sleep outcomes, suggesting guidelines warrant further investigation. WHAT'S KNOWN ON THIS SUBJECT: Current guidelines recommend not using screens, undertaking physical activity, or eating dinner in the hour before bed to ensure healthy sleep. However, these are predominantly based on questionnaires and cross-sectional data, which are prone to bias and cannot determine causality. WHAT THIS STUDY ADDS: Using objective measures and a more powerful temporal design, we show that screen time, moderate-to-vigorous physical activity, and consumption of food and beverages have little impact on subsequent sleep that night, suggesting a revision of relevant guidelines could be considered.