Abstract
Oobjectives: 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 four nights in 83 youth (37% indigenous Māori, 42% female) aged 11–14.9 years. Food/beverage intake was measured via three 24-hour diet recalls, and sleep using Axivity accelerometers (8 nights). Associations were estimated using a repeated measure analysis with mixed effects regression models using sleep variables as the outcome, pre-bed 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 (interquartile range [IQR] 23–40). Screen use did not significantly impact total sleep time (mean difference; 95% CI: 16 minutes; -7, 38) or other sleep outcomes, but did extend sleep latency by 84% (equivalent to 23.1 minutes). 22% of participants undertook MVPA 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 1465kJ (IQR 713–2134). No significant associations were observed between any dietary variables and any sleep outcome.
Conclusions: Few youth adhere to current pre-bed 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.
Clinical Trial Registration: Australian New Zealand Clinical Trials Registry - ACTRN12621000193875 http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=380926