We do it every night, and over the course of our life we will spend approximately a third of our time doing it: sleep. But what is it? Doctors and scientists are really just beginning to understand all the important ways that sleep affects our health and well-being — and all of the reasons we do it.
According to Rafael Pelayo, MD, clinical professor of psychiatry and behavioral sciences and a sleep specialist at the Stanford Sleep Medicine Center in Redwood City, California, “Sleep is a natural, restorative, physiological process characterized by a perceptual disengagement [meaning you tune out from whatever’s going on around you], and must be rapidly reversible.”
Sleep experts at Harvard Medical School’s Division of Sleep Medicine use a similar definition for sleep. They say it can be characterized as: (1)
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A period of being less active
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A function of the body typically associated with a lying down posture and closed eyes
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A process whereby you’re less responsive to external stimuli
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A state of consciousness that’s easy to get out of (unlike other states of consciousness, such as hibernation or coma)
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Being associated with certain brain wave activity patterns and certain physiological changes, including a drop in blood pressure and body temperature
Regardless of the words used to describe it, the bottom line is that we need sleep to function, Dr. Pelayo says. It’s a critical process that allows the body to function and stay healthy — and it’s especially important for the brain.
“The entire body takes advantage of sleep,” Pelayo explains. For example, the kidneys slow down production of urine and digestion slows in the gut. (2) “But sleep is really how the brain gets reset for the next day. Sleep restores the brain.”
That means not getting enough sleep or good quality sleep will damage many systems of the body and over time can contribute to risk of chronic disease and health problems, but the most immediate consequences of not sleeping that you’ll notice are those that affect your mind and thinking.
By Sarah DiGiulio Medically Reviewed by Samuel Mackenzie, MD, PhD
