The role of prescribed napping in sleep medicine.

Napping, when its timing and duration are designed properly, has the potential to improve our daily lives. Laboratory findings indicate that scheduled napping promotes waking function after normal sleep at night, and also counteracts decreased alertness and performance under conditions of sleep deprivation. Since these effects are evident even with naps shorter than 30 min, shiftwork problems may be alleviated by the short nap at the workplace. Multiple short naps are effective in managing excessive daytime sleepiness in narcoleptic patients under medication. The therapeutic usefulness of napping in other sleep disorders, however, remains to be established. Epidemiological studies suggest a decrease in the risk of cardiovascular and cognitive dysfunction by the practice of taking short naps several times a week. Sleep inertia occurs immediately after napping, but its severity can be minimized by avoiding long naps that may result in awakening from deep non-rapid eye movement sleep. Activities during the post-nap period should also be undertaken carefully. To allow the maximum advantage to be gained from napping, more efforts are needed to identify the strategies of napping that are compatible with individual cases including aging, work schedules, and sleep disorders, and to examine their efficacy in real-life settings.