The Influence of a 120-minute Nap on Physical Activity and Subsequent Sleep: Impact of Nighttime Napping during a simulated Night Shift

Abstract

The objective of this study was to analyze the influence of a 120-minute nap on daytime sleep and physical activity in nurses who worked 16-hour night shifts. To accomplish this, we measured the amount of physical activity for different nap groups. The subjects were 10 females (mean age, 21.5 years; standard deviation, 0.71). Three nap groups were established for separate nights during 16-hour night shifts: those taking a nap from 22:00-00:00 (22:00 nap), 00:00-02:00 (00:00 nap) or 02:00-04:00 (02:00 nap). The subjects were fitted with actigraphs, and their average amount of physical activity during the day (steps/min) and the quality of their nap and main sleep were measured. The 22:00 nap group had a longer nap time than 00:00 and 02:00 nap groups. Although the 22:00 nap group had a shorter total main sleep time, sleep efficiency was better. Moreover, fatigue in the 02:00 nap group decreased after the nap, and subjects in the 02:00 nap group had higher average levels of physical activity than the 22:00 nap group. These results suggest that a 120-minute nap starting at 02:00 is the most appropriate for individuals wanting to undertake physical activity after completing a 16-hour shift.