Independent associations of sleep timing, duration and quality with adiposity and weight status in a national sample of adolescents: the UK Millennium Cohort Study

Abstract

Background: There is evidence that short sleep elevates obesity risk in youth, but sleep is a multidimensional construct and few studies have investigated parameters beyond duration. Objectives: To investigate if sleep onset time, duration, latency, and night waking frequency are independently associated with adiposity and weight status in adolescents. Methods: This was a cross-sectional observational study of 10,619 13-15y olds who provided self-reported sleep characteristics and underwent an anthropometric assessment to determine adiposity (body mass index (BMI) z-score and percent body fat (%BF)) and weight status. Adjusted linear and logistic regressions were used to investigate associations. Results: Compared to a sleep onset time before 10pm, later sleep was associated with higher adiposity and higher likelihood of overweight and obesity in boys (after midnight, odds ratio (95% CI): 1.76 (1.19 to 2.60), p=0.004) and girls (between 11-11:59pm: 1.36 (1.17 to 1.65), p=0.002). Compared to sleeping for >9-10 hours, sleeping for [≤]8 hours was associated with higher likelihood of overweight and obesity (boys: 1.80 (1.38 to 2.35), p<0.001); girls: 1.38 (1.06 to 1.79), p=0.016); there was evidence of a U-shaped association in girls for whom >10 hours of sleep was also associated with higher likelihood of overweight and obesity (1.31 (1.06 to 1.62); p=0.014). In girls, relative to a sleep latency of 16-30 minutes, sleep latencies [≥]46 minutes were associated with higher adiposity (46-60 minutes, %BF: 1.47 (0.57 to 2.36), p=0.001) and higher likelihood of overweight and obesity (46-60 minutes: 1.39 (1.05 to 1.83); p=0.020). Often as opposed to never waking in the night was also associated with higher adiposity in girls (BMI z-score: 0.24 (0.08 to 0.41), p=0.004; %BF: 1.44 (0.44 to 2.44), p=0.005). Conclusions: Sleep duration and timing, and sleep quality in girls, are independently associated with adiposity and weight status in adolescence and may be important targets for obesity prevention.