LIGHT EXPOSURE AMONG ADOLESCENTS WITH DELAYED SLEEP PHASE DISORDER: A PROSPECTIVE COHORT STUDY

The objective of this study was to compare light exposure and sleep parameters between adolescents with delayed sleep phase disorder (DSPD; n = 16, 15.3 ± 1.8 yrs) and unaffected controls (n = 22, 13.7 ± 2.4 yrs) using a prospective cohort design. Participants wore wrist actigraphs with photosensors for 14 days. Mean hourly lux levels from 20:00 to 05:00 h and 05:00 to 14:00 h were examined, in addition to the 9-h intervals prior to sleep onset and after sleep offset. Sleep parameters were compared separately, and were also included as covariates within models that analyzed associations with specified light intervals. Additional covariates included group and school night status. Adolescent delayed sleep phase subjects received more evening (p < .02, 22:00–02:00 h) and less morning (p < .05, 08:00–09:00 h and 10:00–12:00 h) light than controls, but had less pre-sleep exposure with adjustments for the time of sleep onset (p < .03, 5–7 h prior to onset hour). No differences were identified with respect to th...