Awakening from a nighttime nap: physiological and cognitive effects of sleep inertia and behavioral countermeasures

To explore the effects of sleep inertia (SI) on physiological responses and cognitive performance, this study involved 1-h night-time sleep arousal experiments with twelve healthy participants. The KSS Scale, EEG, pulse rate (PR), blood pressure (BP), N-back test, and LRT Task were tested. The experimental design included a control condition (no intervention) and two behavioural countermeasure conditions (verbal communication and video watching). Results showed that during the first 10 min affected by SI, the EEG relative power decreased significantly by 72.1%, PR and BP increased significantly by 8.1 and 2.5%, respectively. After countermeasures, KSS scores decreased by 14.12 and 28.25%, EEG increased by 50.00 and 19.23%, the working memory increased by 24.32 and 43.24% for two countermeasures, respectively. Besides, cognitive and physiological responses affected by SI and the effects of countermeasures showed significant sex differences. Future research should explore SI effects across ages and develop more effective countermeasures to address SI.