The 5-minute nap produced few benefits
in comparison with the no-nap control. The 10-minute nap produced immediate
improvements in all outcome measures (including sleep latency,
subjective sleepiness, fatigue, vigor, and cognitive performance), with
some of these benefits maintained for as long as 155 minutes. The 20-
minute nap was associated with improvements emerging 35 minutes after
napping and lasting up to 125 minutes after napping. The 30-minute nap
produced a period of impaired alertness and performance immediately
after napping, indicative of sleep inertia, followed by improvements lasting
up to 155 minutes after the nap.