More than 85% of mammalian species are polyphasic sleepers, meaning that they sleep for short periods throughout the day. Humans are part of the minority of monophasic sleepers, meaning that our days are divided into two distinct periods, one for sleep and one for wakefulness. It is not clear that this is the natural sleep pattern of humans. Young children and elderly persons nap, for example, and napping is a very important aspect of many cultures.
As a nation, the United States appears to be becoming more and more sleep deprived. And it may be our busy lifestyle that keeps us from napping. While naps do not necessarily make up for inadequate or poor quality nighttime sleep, a short nap of 20-30 minutes can help to improve mood, alertness and performance. Nappers are in good company: Winston Churchill, John F. Kennedy, Ronald Reagan, Napoleon, Albert Einstein, Thomas Edison and George W. Bush are known to have valued an afternoon nap.
Naps can be typed in three different ways:
Planned napping (also called preparatory napping) involves taking a nap before you actually get sleepy. You may use this technique when you know that you will be up later than your normal bed time or as a mechanism to ward off getting tired earlier.
Emergency napping occurs when you are suddenly very tired and cannot continue with the activity you were originally engaged in. This type of nap can be used to combat drowsy driving or fatigue while using heavy and dangerous machinery.
Habitual napping is practiced when a person takes a nap at the same time each day. Young children may fall asleep at about the same time each afternoon or an adult might take a short nap after lunch each day.