Collings PJ, Grøntved A, Jago R, et al. - Researchers examined if and how bedtimes and sleep durations are associated with adiposity levels in children and adolescents.

• From 11 international studies, researchers retrieved individual data for 12,247 children (5,819 with follow-up adiposity at 2.3 ± 1.4 years post-baseline) and 3,563 adolescents.

• In children, a correlation of longer sleep durations was consistently evident with lower adiposity markers, and earlier bedtimes were linked with lower BMI z-score.

• In girls and boys, longer baseline sleep duration favorably predicted Δwaist z-score when compared to sleeping < 10 h.

• Lower adiposity was recorded in combined groups that were defined by longer sleep (later-longer and earlier-longer sleep patterns), and in girls, later-longer sleep favorably predicted Δwaist z-score.

• In adolescents, lower BMI z-score was recorded in the whole sample, and also lower waist z-score was recorded in boys in correlation with longer sleep durations and earlier bedtimes.

• The same outcomes were recorded in combined groups that were characterized by earlier bedtimes; for example, lower BMI z-score was observed in correlation with both earlier-shorter and earlier-longer sleep.