ACOUSTIC ENHANCEMENT OF SLOW-WAVE SLEEP IN HEALTHY ADOLESCENTS

Abstract Introduction Adolescents have a stable sleep-need of between 9-10 hours a night, yet a pattern of markedly restricted sleep duration, particularly on school nights, has given rise to an epidemic of sleep deprivation in this population. As demonstrated by large numbers of studies, insufficient, irregular, and/or poor-quality sleep is a risk factor for both mental health problems and learning difficulties. Enhancing slow-wave sleep through non-pharmacological means may be a mechanism for alleviating daytime functional deficits in youth. In this study, we tested the feasibility of enhancing slow-wave sleep in healthy adolescents using a closed-loop, sleep-wearable device (SmartSleep, Phillips-Respironics) which monitors the EEG signal to automatically detect sleep stages, slow-waves, and micro-arousals to deliver acoustic stimulation to enhance SWA. Methods Seventeen healthy adolescents (15.5±1.8 years; 11 female) who endorsed sleep restriction and symptoms of daytime sleepiness participated in a randomized, cross-over study. Participation included wearing SmartSleep for two consecutive 4-night periods at home—one period with acoustic stimulation (STIM) and one without (SHAM). During STIM, SmartSleep monitors the EEG in real-time and delivers acoustic tones (50 ms, 1 second interval between) through embedded headphones at an intensity dynamically modulated by sleep depth. Stimulation is stopped when an arousal or sleep stage-shift is detected. During SHAM recording, the same stimulation protocol is applied with tones played at zero volume. Results No differences were observed in any measure of sleep architecture. A mixed effects linear regression model was used to analyze the impact of condition (STIM vs SHAM) on both cumulative and average SWA during N2N3 and N3 sleep. At the group level, cumulative SWA during N2N3 and average SWA during N3 were significantly increased in STIM relative to SHAM (p=0.01; p=0.02, respectively), while age (p=0.67) and sex (p=0.71) had no effect. Despite the significant group effects, not all youth were responders; an average increase in cumulative SWA (11.5 ± 7.1%) in the STIM condition was observed in 12/17 participants. Conclusion Consecutive nights of acoustic stimulation enhanced SWA in otherwise healthy, sleep-restricted adolescents. These data suggest that acoustic stimulation during sleep may be a viable method for optimizing slow-wave activity and minimizing the emotional and cognitive consequences of sleep restriction during this sensitive developmental period. Support (If Any)