Longer periods of REM occur during morning hours, so morning naps are dominated by REM, midday naps have about equal parts of REM and deep sleep, and evening naps contain more deep sleep.

较长时间的快速眼动发生在早上，所以早上的小睡主要是快速眼动，中午小睡的快速眼动睡眠和深度睡眠的比例大致相等，而晚上小睡的深度睡眠更多。