Napping after complex motor learning enhances juggling performance

Abstract

The present study examined whether a nap after complex motor learning enhanced the following day's physical performance. Eighteen volunteers met the inclusion criteria and were assigned to either a nap (n=9; men=5; mean age=21.0±1.5) or no-nap group (n=9; men=5; mean age=21.9±0.3). Participants practiced juggling in the morning and were tested immediately afterwards. Participants of the nap group were given a 70-minute nap opportunity after juggling practice, while the no-nap group stayed awake. Juggling performance was then tested in the evening (retest-1) and the next morning (retest-2). Two-way analysis of variance (group: nap, no-nap×time: test, retest-1, retest-2) found there was a significant effect of test time and a significant group×time interaction. The juggling performance of both groups improved from test to retest-1, respectively. However, the juggling performance level of the nap group was higher than that of the no-nap group at the retest-1. As predicted, a nap promptly after learning motor skills was associated with subsequently improved performance. Moreover, the juggling performance of the nap group showed additional significant improvements in the retest-2. In the no-nap group, however, there were no significant improvements in the juggling performance after nocturnal sleep. These results demonstrate that the benefits of a nap following learning were further enhanced after nocturnal sleep. The present results may provide justification for introducing nap periods into daily athletic training as an active method to improve performance.

Keywords: Memory consolidation; Motor learning; Motor skills; Nap; Sleep.

Fig. 1

Experimental design practice session: subjects practiced three-ball cascade juggling after watching an instructional DVD. Test session: juggling performance was evaluated in five 3 min trials, during which subjects continued juggling for as long as possible. After the test session, subjects in the nap group took a 70-minute nap starting at 14:00, while the control subjects stayed awake. Retest-1 session: juggling performance re-tested at 17:30. Retest-2 session: juggling performance re-tested at 10:30 the following morning.

Fig. 2

Comparison between the nap and no-nap groups of the mean number of catches while juggling. The solid line identifies the nap group, while the dotted line identifies the no-nap group. Error bar shows the standard error. **p<0.001. *p<0.05. n.s. not significant.

Fig. 3

The assessment of subjective fatigue, concentration, and sleepiness. The black bars indicate the nap group, while the white bars identify the no-nap group. Error bar, standard deviation. *p<0.05 in the nap group.