0210 Effects of Artificial Dawn on Sleep Inertia in Alertness, Mood, and Cognitive Performance in Healthy Participants

Abstract Introduction Sleep inertia is known as a transitory period from sleep to wakefulness. During the transition, people may suffer from confusion, disorientation, sleepiness and impaired performance. Studies have shown that light exposure could elicit numerous effects on human physiology and behavior. Here we investigated whether dawn-simulated light could be a countermeasure of reducing morning sleep inertia in young healthy adults. Methods Sixteen participants (9 females, mean age: 19.78 ± 0.37 years) were enrolled based on strict screening procedure. Three different lighting settings (separated by at week) were administered in the morning after a 6.5-h sleep restriction night: dawn-simulated light (polychromatic light gradually increasing from 0 to 250 lx during 30 min before scheduled wake-up time), constant light and control (no artificial dawn) condition. Cognitive tasks measuring attentional processes and inhibitory capacity, and questionnaires assessing subjective alertness and mood were performed two hours before habitual bedtime and at regular intervals for three hours during scheduled wakefulness in the morning in a three-way crossover laboratory design. While sleep quality and sleep duration were concurrently monitored by actigraphy and were treated as potential confounders in the present study. Results Participants’ alertness and positive mood were significantly reduced after waking up (palertness