Rapid eye movement (REM) sleep occurred infrequently.

A greater proportion of slow-wave sleep (SWS) was obtained in nap opportunities of 40 and 60 min compared with 20 min. During the nap opportunities, sleep onset latency was short and sleep efficiency was high. Sleep on the baseline night and during the naps was recorded polysomnographically. After a baseline 8 h time-in-bed, healthy young males (P1 mean age 25.1 yr P2 mean age 23.2 yr) underwent either в‰€20 h (P1) or в‰€30 h (P2) of sleep deprivation on four separate occasions, followed by nap opportunities of 0, 20, 40, and 60 min. Each protocol included 12 participants in a within-subjects design in a controlled laboratory environment. The objective of this study was to evaluate the effectiveness of nap opportunities of 20, 40, or 60 min for maintaining alertness and performance 1.5вЂ“6 h post-nap in simulated nightwork (P1) or extended operations (P2). The time course of performance after naps of differing durations is thus an important consideration in weighing the benefits and risks of napping in workplace settings.

Longer naps may not only result in longer-lasting benefits but also increase the risk of sleep inertia immediately upon waking. Napping has been shown to improve performance and alertness after periods of prolonged wakefulness and sleep loss. Operational settings involving shiftwork or extended operations require periods of prolonged wakefulness, which in conjunction with sleep loss and circadian factors, can have a negative impact on performance, alertness, and workplace safety.

Nap durations