Abstract
The purpose of this study isto investigate the effect of dawn simulated light and sleep stages just before awakening on subjective feelings of awakening. A counterbalanced study was performed on different one night, totally two nights, one of which was control day (no dawn simulation), and another one was experimental (dawn simulation).
Twenty healthy participants took part in a laboratory protocol. PSG was recorded during nocturnal sleep. The amount of light before awakening was estimated by the sleeping position per second. Subjective sleepiness evaluated using OSA sleep inventory is significantly reduced in the dawn condition as compared with control condition for participants awaken from NREM sleep (p < 0.05). In participants awaken from NREM sleep with appropriate amount of light exposure before awakening, sleepiness also shows a significant decrease (p < 0.01) as compared with control condition. However in participants awaken from phasic REM sleep, there is no significant difference in sleepiness between two conditions. In participants awaken from NREM sleep, sleepiness is significantly correlated with the amount of light exposure before awakening (r=0.56, p < 0.05). These results suggest that for the better awakening, not only appropriate amount of light exposure before awakening but also a sleep state just before awakening should be considered.
https://ror.org/00965ax52 
