Effects of Napping in Sleep-Restricted Adolescents

57 participants (aged 15 to 19 years old) were grouped into nap and no nap groups. Both groups took part in a 15-day protocol that started with 2 9-hour adaptation and baseline nights, followed by two successive cycles of sleep restriction (5-h time-in-bed \[TIB\]; 01:00-06:00) and recovery (9-h TIB; 23:00-08:00) intended to simulate the weekday sleep loss and weekend attempt to 'catch up' that are familiar to high school students. The nap group received a 1-hour nap opportunity at 14:00 following each sleep-restricted night, while participants in the no nap group watched a documentary. Sleep was monitored with polysomnography on 9 selected nights. Cognitive performance, subjective sleepiness, and mood were assessed 3 times daily (10:00, 15:45, and 20:00). All participants stayed in air-conditioned, twin-share bedrooms with en-suite bathrooms. Bedroom windows were fitted with blackout panels to ensure participants were not woken up prematurely by sunlight. Earplugs were also provided, and participants were allowed to adjust the temperature of their bedrooms to their personal comfort. 3 main meals were served each day, with snacks being provided for upon request. Caffeinated drinks, unscheduled sleep, and strenuous physical activities were prohibited. Outside of scheduled sleep, meal, and cognitive testing times, participants spent the majority of their free time in a common room that was illuminated by natural and artificial lighting. They were allowed to read, play non-physically exerting games, watch videos, and interact with research staff and other participants. Participants were under constant supervision by the research staff.