Good sleep, bad sleep! The role of daytime naps in healthy adults.
OBJECTIVE
Millions of people all over the world take a nap during the day. People nap out of habit, because they are sleep-deprived as a result of a sleep disorder, or after a long work shift. Individuals of all age groups, from infants to the elderly, indulge in an afternoon nap. This review examines the benefits and drawbacks of daytime naps in healthy adults.


RESULTS
A nap during the afternoon restores wakefulness and promotes performance and learning. Several investigators have shown that napping for as short as 10 min improves performance. Naps of less than 30 min duration confer several benefits, whereas longer naps are associated with a loss of productivity and sleep inertia. Recent epidemiological studies indicate that frequent and longer naps may lead to adverse long-term health effects.


CONCLUSIONS
A nap of less than 30 min duration during the day promotes wakefulness and enhances performance and learning ability. In contrast, the habit of taking frequent and long naps may be associated with higher morbidity and mortality, especially among the elderly. The benefits of napping could be best obtained by training the body and mind to awaken after a short nap.
Dhand
Rajiv
R
Harry S. Truman VA Hospital, Columbia, Missouri, USA. dhandr@health.missouri.edu
Sohal
Harjyot
H
D002940:Circadian Rhythm; D004526:Efficiency / Q000502:physiology*; D006801:Humans; D007858:Learning / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology*