Sleeping is fun, and one of the most fun ways to sleep is daytime napping.
There are many ways of napping. Different lengths, locations, and times of day. Some people have a regular nap in the afternoon (common in toddlers and retired people). Others have a catnap during their lunch breaks. Opportunity and preferences play a big part in napping behavior.
Working adults who nap usually do so in short bursts – the power nap. Weekends present the opportunity for longer naps. Power naps do not last long enough to get to slow-wave sleep. Even short naps can be refreshing.
Toddlers and small children usually need an afternoon nap, and this nap lasts an hour or more. In contrast to adult nappers, toddlers more often go into deep sleep. Kids need lots of deep sleep to support their growth.
Some investigators distinguish between appetitive nappers and
replacement nappers. - see
Appetitive nappers can nap at almost any time, and do so often to "tune out" of their surroundings. Replacement nappers are trying to catch up on sleep. Appetitive nappers can nap even when not sleepy, like an afternoon nap. Replacement nappers are usually not in the mental state or habit that allows them to sleep at will. These are generalizations, of course, and not necessarily fixed.
Another way to classify napping is by saying some naps are prophylactic and some are recuperative, respectively before or after sleep loss. The planned naps before anticipated periods of busy work can raise performance and cut the risk of sleepiness during times when a person needs to be at the top of his or her game.
Research continues to show that daytime napping can improve mental performance in adults, which led to enthusiasm behind the mid-day power nap as well as preparation naps for hurry-up-and-wait occupations such as surgeon and airline pilot. National Geographic even had an article in which they compared the brain to an email system, "sleep—and more specifically, naps—is how you clear out your inbox." That’s too simplistic, of course, but sleep in general makes us more receptive to learning.
So we know naps can help us remember things we just learned, but are they better than equivalent period of time awake a relaxing or watching television?
Yes, the time spent in napping is better for remembering than the time spent awake.
Longer sleep durations such as nighttime sleep are even better for memory than daytime naps. However, research has established that the gains in improved memory occur in the first half of the night. A sleep period of 3.5 hours is pretty much as effective as a period of 7 hours.
This meshes with the idea that REM (which occurs more in the latter half of the period) is not important in memory formation. This study also confirmed that Stage 2 sleep (particularly early in the night) is important in learning new motor skills.
Naps over 30 minutes usually bring post-nap inertia, though. If the sleeper goes into State 3, slow-wave sleep, it will be harder to wake up. The cognitive benefits of the longer naps last longer, too.
Children are great nappers, partly because they are learning so fast. Many preschools and kindergartens incorporate time for napping in the child’s day. Research has shown naps help children remember things learned earlier in the day and that the children who get the most cognitive benefits are those who nap habitually. When a child skips a regular nap and makes up for the lost sleep time by extending nighttime sleep, the cognitive benefits are not recovered in the makeup sleep.
Hammocks are great for napping, too, and researchers have found that the rocking motion of the hammock facilities falling asleep.
Swinging makes you fall asleep faster and extends the length of the nap, which is why the hammock and similar moving platforms are ideal for appetitive napping. Riding in a car helps some people sleep (one hopes they are passengers, not the driver).
Insomniacs, especially those attempting sleep restriction therapy, are discouraged from daytime napping because it could make it harder to sleep at night.
Napping can be taken as a sign of excessive daytime sleepiness, a symptom of many sleep disorders, but this is an example of how we look at sleep differs whether we are looking for pathologies or recreation. Recreational and appetitive naps are fun, and not a sign of a disorder.