A nap is a short period of sleep, typically taken between the hours of 9am and 9pm as an adjunct to the usual nocturnal sleep period. Naps are most often taken as a response to drowsiness during waking hours. A nap is a form of biphasic or polyphasic sleep, where the latter terms also include longer periods of sleep in addition to one single period. Cultural attitudes toward napping during the work day vary. In many Western cultures, children and the elderly are expected to nap during the day and are provided with designated periods and locations to do so. In these same cultures, most working adults are not expected to sleep during the day and napping on the job is widely considered unacceptable. Other cultures (especially those in hot climates) serve their largest meals at midday, with allowance for a nap period (siesta) afterwards before returning to work.