Is the power nap really powerful? Can we make up for lost sleep by sacking out on Saturday? MSN Health & Fitness sought a few answers from the Land of Nod.
Do we really need eight hours of sleep per night?
Not necessarily, but that's the average for healthy adults. According to the National Institutes of Health, when healthy adults are given unlimited opportunity to sleep, they're on the pillow eight to eight-and-a-half hours a night. Most sleep experts recommend between seven and nine hours to be at one's optimum performance mentally and physically.
The amount of sleep needed to be at one's best is called "basal sleep" time. Basal sleep is forever in competition with "sleep debt," which is the total sleep we lose due to certain sleep disorders, restless partners or screaming infants (but parents cherish every waking moment … right?). We constantly need basal sleep to pay down our sleep debt.
Most people have an innate sense of whether they're getting enough shut-eye (for a quick evaluation of your own sleep status, check out the Epworth Sleepiness Scale). According to the Sleep In America poll, Americans in 2005 averaged almost seven hours per night, while back in 1910 we averaged nine hours. What would you give up for an extra two hours of sleep tonight?
Can we catch up on sleep during the weekend? Is this healthy?
Yes, you can effectively catch up on sleep—and no, it's not particularly healthy.
The body and brain share a remarkable ability to recover when we don't treat them as well as we should. When you skimp on sleep, you miss more of the REM and other cycles that keep the brain's memory, concentration, motor skills, and emotional controls in good working order. That's why someone on three hours' sleep can stay awake but is more likely to fumble with the car keys or put on shoes that don't match. Nonetheless, the brain will begin to reset itself after a good night's sleep.
Though the body is resilient as well, all of its major systems require the slowed pace and reduction of stimuli that come with adequate rest. As the National Sleep Foundation describes in Sleep-Wake Cycle: Its Physiology and Impact on Health, scientists believe the body repairs itself during sleep with a number of biochemical and physiological processes, and that without restorative sleep our systems become more vulnerable. A 2002 study, for example, showed that sleep helps fortify the immune system: When flu shots were administered to two groups of men, those who slept normally for 10 nights in a row had twice as many flu-fighting antibodies as those who slept just four hours per night.
Dr. Michael Twery, director of the National Center on Sleep Disorders at the National Heart, Lung, and Blood Institute, offers additional words of warning: "Recent findings indicate that regularly sleeping less than seven hours each night is associated with potentially serious health conditions such as obesity, diabetes, and cardiovascular disease."
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