The purpose of this study is to investigate the count-characteristics of wrist actigraphy in basic human activities and to discuss the agreement of sleep-wake identification between polysomnography (PSG) and wrist actigraphy during nocturnal sleep. There was a distinct distribution of actigraphy counts over the studied activities. The evaluation of sleep-wake scoring using the wrist actigraphy agreed 96.9% with the polysomnographic scoring during nocturnal sleep.