Daytime naps improve motor imagery learning.

Sleep is known to contribute to motor memory consolidation. Recent studies have provided evidence that a night of sleep plays a similar functional role following motor imagery (MI), while the simple passage of time does not result in performance gains. Here, we examined the benefits of a daytime nap on motor memory consolidation after MI practice. Participants were trained by MI on an explicitly known sequence of finger movements at 11:00. Half of the participants were then subjected (at 14:00) to either a short nap (10 min of stage 2 sleep) or a long nap (60-90 min, including slow wave sleep and rapid eye movement sleep). We also collected data from both quiet and active rest control groups. All participants remained in the lab until being retested at 16:00. The data revealed that a daytime nap after imagery practice improved motor performance and, therefore, facilitated motor memory consolidation, as compared with spending a similar time interval in the wake state. Interestingly, the results revealed that both short and long naps resulted in similar delayed performance gains. The data might also suggest that the presence of slow wave and rapid eye movement sleep does not provide additional benefits for the sleep-dependent motor skill consolidation following MI practice.