ABSTRACT
OBJECTIVES: Delayed sleep phase syndrome (DSPS) is characterized by difficulties in falling asleep and waking up at a desired time. Dawn simulation is a technique using a light that gradually increases in intensity before awakening in the morning, to imitate a natural sunrise. It has been found to be effective in decreasing both morning drowsiness and difficulty in awakening as well as treating symptoms of seasonal affective disorder. The aim of this study was to determine whether dawn simulation is helpful in decreasing difficulty in morning awakening and daytime sleepiness in adolescents with DSPS. METHODS: Twelve adolescents with DSPS participated in a 2-week dawn simulation trial. Each subject self-assessed level of difficulty in awakening, morning drowsiness and daytime sleepiness during a 2-week baseline period and a following 2-week trial period with dawn simulator. Subjects used Stanford Sleepiness Scale (SSS) for measuring morning drowsiness and Epworth Sleepiness Scale (ESS) for measuring daytime sleepiness. Difficulty in awakening was assessed by a single-item questionnaire. RESULTS: Dawn simulation trial decreased morning drowsiness (p=0.016) and daytime sleepiness (p=0.013) significantly compared to baseline. It also seemed to improve difficulty in awakening, but the effect was not statistically significant (p=0.092). CONCLUSION: Dawn simulation may help waking up in the morning and may improve daytime functioning by deceasing both morning drowsiness and daytime sleepiness in adolescents with DSPS.