Fig. 1From: Objective and subjective measures of sleep initiation are differentially associated with DNA methylation in adolescentsA comparison of sleep initiation measurement methods for two sample participants. Bedtime, sleep onset latency (SOL), and sleep onset time (SOT) are depicted for polysomnography (PSG), actigraphy (ACT), and self-report (SR). PSG SOT is measured as the onset of sleep stage N2, depicted as S2. ACT SOT is calculated from movements and can underestimate sleep latency. SR is measured using participant questionnairesBack to article page