Importance Inadequate sleep duration and quality increase the risk of obesity. Sleep timing,
while less studied, is important in adolescents because increasing evening preferences
(chronotypes), early school start times, and irregular sleep schedules may cause circadian
misalignment. Objective To investigate associations of chronotype and social jet lag with
adiposity and cardiometabolic risk in young adolescents. Design, Setting, and Participants
Starting in 1999, Project Viva recruited pregnant women from eastern Massachusetts …