Nap

A nap is a short period of sleep, typically taken during daytime hours as an adjunct to the usual nocturnal sleep period. Naps are most often taken as a response to drowsiness during waking hours or as a means to supplement before or after loss of sleep. A nap is a form of biphasic or polyphasic sleep, where the latter terms also include longer periods of sleep in addition to one period. There are... (Wikipedia)