Influence of a 120-minute Nap on the Amount of Physical Activity and Subsequent SleepQuality:

The objective of this study is to clarify the influence of a 120-minute nap (assuming a nurse works a 16-hour night shift from 16:00–09:00) on subsequent sleep and amount of activity. To do so, the amount of physical activity was measured for each interval of nap time. The subjects were 10 females. Three nap start time conditions were established for separate nights during the 16-hour night shift: 22:00–00:00 (22:00 nap), 00:00–02:00 (00:00 nap), and 02:00–04:00 (02:00 nap). The target group was fitted with an Actigraph, and their average amount of physical activity during the day (count/min) and the quality of their daytime sleep were measured.

The start time for daytime sleep was earlier for the 02:00 nap than the 00:00 nap, and the sleeping hours were shorter for the 02:00 nap than the 22:00 nap. Moreover, the sleep efficiency of the nap starting at 22:00 was lower than the naps starting at 00:00 and 02:00. The average amount of daytime physical activity was significantly higher for the 02:00 nap than the 22:00 nap.

The 02:00 nap allowed for earlier daytime sleep than the other two conditions. Moreover, as the sleeping hours were shorter for this condition and it had the highest amount of average physical activity of the three conditions, this nap interval appears to have the fastest recovery from fatigue of any time interval. From these results, it is suggests that taking the 02:00 nap is superior for a person wanting to undergo activities after completion of a shift.