ObjectiveaaPrevious findings suggest that hand movement laterality is reversed during sleep. The present study aimed to verify this phenomenon and evaluate whether the extent of reversal is correlated with the severity of sleep apnea. MethodsaaA total of 184 participants (mean age: 44.5±13.0 years; 81.5% males) wore actigraphs on both hands during sleep, and nocturnal polysomnography was simultaneously performed. ResultsaaActigraphic indices of hand movement were significantly higher for the left hand than those for the right hand (p<0.001), including total activity score, mean activity score, mean score in active periods and fragmentation index. Additionally, calculated differences between the fragmentation index for the left versus right hands were significantly correlated with the apnea-hypopnea index (AHI, r=0.149, p=0.032). The AHI was not significantly correlated with differences in hand movement between both hands movement assessed by total activity score (r=0.004, p=0.957), mean activity score (r=0.011, p=0.876), mean score in active periods (r=-0.080, p=0.255). ConclusionaaMore severe symptoms of obstructive sleep apnea was associated with larger degree of hand movement reversal at night. This result support the theory that homeostatic deactivation occurs in the dominant hemisphere during sleep.