Although napping
habits vary across cultures, research shows that napping is a common feature of healthy adult sleep-wake
behavior, even when no sleep debt was incurred the night before the
nap[9]. So why don't we all require naps? Apparently, napping can be
easily suppressed (such as when one is at work) because naps "tend to occur as transient
events in an otherwise rising circadian function of behavioral and physiological activation"[9]. In 1994, Aschoff discovered that neither the duration of the main sleep
nor the circadian cycle is affected by napping[10].