A randomized controlled trial of the effects of bright light and melatonin for delayed sleep phase disorder

Abstract

Introduction Delayed sleep phase disorder (DSPD) is a circadian rhythm sleep disorder. Patients with DSPD have problems initiating sleep if they go to bed at a conventional time and they have serious problems waking at desired times. In the present study we investigated short- and long-term effects of timed bright light and exogenous melatonin treatment alongside gradually advanced rise times in adolescents/young adults with DSPD in a randomized controlled two- week trial with an open label 3-month follow-up study. Materials and methods Forty patients (16–25 years) diagnosed with DSPD were recruited to participate. The participants were randomized to receive treatment for 2 weeks in one of four treatment conditions: dim light + placebo capsules, bright light + placebo capsules, dim light + melatonin capsules or bright light + melatonin capsules. In the follow-up study, participants were re-randomized to either receive treatment with the combination of bright light and melatonin or no treatment in an open label trial for three months. Light and capsules were administered alongside gradual advancement of rise times. The main end points were sleep and daytime function as assessed by sleep diaries, actigraphy, sleepiness/fatigue recordings, cognitive function and circadian phase (assessed by salivary dim light melatonin onset (DLMO)). Results During the two-week intervention, the timing of sleep and DLMO were advanced in all treatment conditions with no interaction effects (two-way ANOVA); about one hour advance of bed time, 2 h advance of rise time and two hours advance of DLMO in all four groups. Sleep duration was reduced with one hour. Subjective sleepiness, fatigue and cognitive function also improved significantly after two weeks of treatment, again with no interaction effects. At three- month follow-up, the no-treatment group had returned to baseline on all measures, whereas the treatment group had maintained an advanced sleep phase as well as improved scores on sleepiness, fatigue, and cognitive function. Sleep duration had increased. Conclusion Gradual advancement of rise time produced a phase advance and an improved daytime function during the two-week intervention, irrespective of treatment condition. Termination of treatment caused relapse into delayed sleep times and poor daytime function, whereas long-term treatment with bright light and melatonin allowed maintenance of the advanced sleep phase and improved daytime function. Acknowledgements Thanks to all the participants.