The Science On Sleep: Why Not All Sleep Is Created Equal
Sleeping less than seven hours may not be the best because you miss out on hitting your ‘power sleep’ stride––where a restorative type of sleep called rapid eye movement thrives.
Sleep involves several distinct stages with special functions at work. Slow wave sleep (meaning our brain waves are slow) is a time for tissue growth and repair. Key immune system chemicals (such as interleukin) increase during slow wave sleep. Losing this restorative sleep hampers immune functioning.
REM (rapid eye movement) sleep helps us to keep our bearings physically and mentally. During REM sleep, our memory circuits undergo special strengthening processes. This occurs through the stimulation of neurons. James B. Maas, PhD, compares this stimulation to the effect of weightlifting upon muscles.
Neurotransmitters act as the brain’s chemical messengers. They’re in limited supply and they decrease during the day. During REM sleep, those neurotransmitter stores build up again. This provides us with the mental juice we need to learn, remember, and function physically at our highest possible levels.
Here’s the kicker: We enter a REM phase after 90 minutes of sleep and then again every 90 minutes that we stay asleep. But the length of the REM phases double each time. It grows from nine minutes the first time, to 18 the second, 36 the third and—if we sleep long enough—to 72 minutes in the wee hours of the morning. Meaning: We get most of this vital REM sleep after we’ve been asleep about six and one-half hours. The person who tries to do more by sleeping less than seven hours misses the richest time for “power sleep.”
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Printed as “The quest for sleep,” Spring 2006