The former is associated with dreaming and thought to be important for learning, and the latter is connected with physical recovery-the proverbial recharging of one's batteries. A sleeper will regularly shift back and forth between these two forms of sleep, with four to five cycles during an average night.
兩種睡眠的機能不同，速眼動與作夢、學習有關；非速眼動與身體系統的修復有關，兩者有規則地交錯循環，一個晚上約循環四、五次。