Can exercise regulate the circadian system of adolescents? Novel implications for the treatment of delayed sleep-wake phase disorder.

Adolescents are vulnerable to inadequate sleep due to a unique constellation of risk factors. In particular, the puberty-related phase delay in the timing of the circadian system postpones the onset of sleep. Resultantly, disordered sleep is common among teenagers and young adults, with the most common sleep problem being delayed sleep wake-phase disorder (DSWPD). Although current treatments for DSWPD show promise, novel ways to improve our youth's sleep are needed. The purpose of this review is to critically evaluate the evidence for the role of exercise as a method to shift and/or regulate circadian timing, and thus improve sleep, in adolescents and young adults. A growing body of evidence suggests that nocturnal exercise can delay circadian timing. However, exercise administered at different times of the 24-h day may result in phase advances, particularly when the timing of exercise is gradually advanced in small daily increments. The implications of these results for young people's sleep health are discussed and suggestions are provided for ways that exercise could be used clinically, to improve the treatment of DSWPD.