An afternoon nap(午睡)is one of the joys of life, although too much napping could signal all is not well. In some cultures, people will have a daily nap—this is fine. The warning comes when people start sleeping during the daytime, when they did not sleep before. There is certainly a good reason to believe that daytime sleepiness—as in the Alzheimer's disease study—can be a marker of an underlying condition.
For most people, napping during the day is mainly a sign that you are not getting enough sleep at night, says Dr. Neill Stanley, a sleep expert. "If you feel sleepy during the day, you should think about taking a nap. That is what the body needs —it doesn't need to be kept awake with caffeine. It needs sleep. "The feeling we should notice is "sleepiness", he says. "It's not tiredness, which could be more psychological and linked to stress."
So how do you nap well? The key thing, says Stanley, is how long your nap lasts. Choose either a 20-or 90-minute nap. "When you fall asleep, you'll quickly go through the lighter stages of sleep into your first period of deep sleep. You don't want to wake up because that's when you wake and feel worse than you did before. "Napping for 20 minutes means you will wake up before you go into deep sleep; napping for 90 minutes means you'll complete a sleep cycle.
Once you factor in the time it takes to fall asleep—"Some people are better at napping than others but, "says Stanley, "a healthy adult will fall asleep in between 5 and 12 minutes. "—you can set an alarm, allowing a 30-to 40-minute period for a short nap, and up to two hours for a longer one.
A good time to nap is during the body's natural dip in the afternoon, between 2 p. m. and 4p. m. "You don't really want to be napping much past that because then you are going to be eating into your night-time sleep, "Stanley says. The point, he stresses, is to get good night-time sleep, which would ensure you probably don't need to nap at all.
