Elderly people
Sleep and circadian rhythms change dramatically with
age [20]. Sleep problems are very common in elderly
people, affecting their quality of life. As in young adults,
a brief nap is believed to improve alertness and
performance in the elderly, too. Indeed, according to
a study by Tamaki and colleagues (2000) [12], elderly
subjects (mean age, 73 years) showed reduced sleepiness
and fatigue and improvement in performance in a
visual detection task after a 34-min nap commencing at
13:00 h (polysomnographically de®ned sleep of
24 min). These effects of napping were observed for
the subsequent 2 h. Actigraphic monitoring of these
elderly subjects over a 1-week period also revealed
that they took 4.6 naps per week, and that each nap
starting at 13:51 h, on average, lasted for 38 min.
Notably, there were no signi®cant differences in
nocturnal sleep variables between nap days and no-nap
days, which suggests the absence of any interference
with the following night's sleep.