Bedroom media, sedentary time and screen-time in children: a longitudinal analysis

BACKGROUND: Having electronic media in the bedroom is cross-sectionally associated with greater screen-time in children, but few longitudinal studies exist. The aim of this study was to describe longitudinal patterns of ownership and examine cross-sectional and longitudinal associations of bedroom media with children’s sedentary behaviour. METHODS: Data are from the Sport, Physical activity and Eating behaviour: Environmental Determinants in Young people (SPEEDY) study, collected at 3 time-points: baseline (2007, T(0;) age 10.3 ± 0.3 years), 1-year (T(1y)) and 4-year (T(4y)) follow-up. For each assessment, 1512 (44.9% male), 715 (41.0% male), and 319 (48.3% male) participants provided valid accelerometer data. Outcome variables were accelerometer-assessed sedentary time and self-reported screen-time. The presence of a television or computer in the bedroom was self-reported by participants and a combined bedroom media score calculated as the sum of such items. Cross-sectional and longitudinal associations between bedroom media and each outcome were examined using multi-level linear regression. RESULTS: Bedroom TV ownership fell from 70.9% at T(0) to 42.5% at T(4y). Having a TV in the bedroom (beta; 95% CI*100, T(0): -1.17; -1.88, -0.46. T(1y): -1.68; -2.67, -0.70) and combined bedroom media (T(0): -0.76; -1.26, -0.27. T(1y): -0.79; -1.51, -0.07) were negatively associated with objectively measured weekly sedentary time at T(0) and T(1y). Having a computer in the bedroom (beta; 95% CI, T(0): 0.15; 0.02, 0.29. T(4y): 0.35; 0.10, 0.60) and combined bedroom media (T(0): 0.09: 0.01, 0.18. T(4y): 0.20; 0.05, 0.34) were positively associated with screen-time at T(0) and T(4y). Relative to participants without a computer throughout the study, children that had a computer in their bedroom at T(0) but not at T(4y) (beta; 95% CI for change in screen-time: -8.02; -12.75, -3.29) reported smaller increases in screen-time. CONCLUSIONS: The bedroom media environment changes with age and exhibits a complex relationship with children’s sedentary behaviour. Modifying children’s bedroom media environment may impact upon screen-time but appears unlikely to influence overall sedentary time.