How Much Sleep Do You Need? The body needs 7-8 hours of sleep per day; 6 hours or less triples your risk of a car accident. (Interestingly, too much sleep–more than 9 hours–can actually be harmful for your health; recent studies show that those who sleep more than 9 hours per day don’t live as long as their 8-hour-sleep counterparts!)

The Effects of Missed Sleep: Sleep is cumulative; if you lose sleep one day, you feel it the next. If you miss adequate sleep several days in a row, you build up a ‘sleep deficit’, which impairs the following:

  • Reaction time
  • Judgment
  • Vision
  • Information processing
  • Short-term memory
  • Performance
  • Motivation
  • Vigilance

Fatigued people also experience more moodiness, aggressive behaviors, burnout and more stress.

The Benefit of a Power Nap: Studies show that 20 minutes of sleep in the afternoon provides more rest than 20 minutes more sleep in the morning (though the last two hours of morning sleep have special benefits of their own). The body seems to be designed for this, as most people’s bodies naturally become more tired in the afternoon, about 8 hours after we wake up.

How Long Should I Sleep? When you sleep you pass through different stages of sleep, known together as a sleep cycle. These stages include light sleep, deep sleep (which is believed to be the stage in which the body repairs itself), and rapid-eye movement sleep, or REM sleep (during which the mind is repaired).

Many experts advise to keep the nap between 15 and 30 minutes, as sleeping longer gets you into deeper stages of sleep, from which it’s more difficult to awaken. Also, longer naps can make it more difficult to fall asleep at night, especially if your sleep deficit is relatively small. However, research has shown that a 1-hour nap has many more restorative effects than a 30-minute nap, including a much greater improvement in cognitive functioning. The key to taking a longer nap is to get a sense of how long your sleep cycles are, and try to awaken at the end of a sleep cycle. (It’s actually more the interruption of the sleep cycle that makes you groggy, rather than the deeper states of sleep.)

As there are pros and cons to each length of sleep, you may want to let your schedule decide: if you only have 15 minutes to spare, take them! But if you could work in an hour nap, you may do well to complete a whole sleep cycle, even if it means less sleep at night. If you only have 5 minutes to spare, just close your eyes; even a brief rest has the benefit of reducing stress and helping you relax a little, which can give you more energy to complete the tasks of your day.

Tips For a More Effective Nap If you want to obtain more sleep, and the health benefits that go with getting enough sleep, here are some tips for more effective napping and sleep at night:

  • Avoid caffeine after 3pm. It’s a stimulant that can disrupt your sleep and stay in your system longer than you think; its half-life is four to six hours!
  • If you don’t want to nap a long time, set an alarm.
  • If you don’t have time for a power nap, or don’t feel comfortable napping during the day, try meditation; it gives your body a rest and produces slower brain waves similar to sleep.