Nap timing
The timing of a nap determines its effects. Given the
feasibility for most daytime workers, napping during
the post-lunch rest period is the most likely to be
complied with [5, 6]. However, one could argue that
midafternoon is a good time for napping because this
period corresponds to the peak of daytime sleepiness
[19]. This view is supported by recent ®ndings from
two well-designed studies [8, 9]. A 25-min nap that
commenced at 12:20 h increased alertness by both
subjective and objective criteria as compared with no
nap, but did not increase the cognitive performance,
whereas a 27-min nap that commenced at 14:00 h was
effective in improving both alertness and cognitive
performance during the next 2.5 h [8, 9]. Despite these
merits, people at work or at school are typically not
permitted to nap in the midafternoon.