It may come as a surprise that beyond seven hours there were consistent signs, both acutely and during follow-up, of cognitive and mental health decline, as well as unfavorable changes in brain structure. Also consistent is the relationship of long sleep (more than eight hours) and heightened all-cause mortality (by approximately 30%) that was previously established among nearly 1.4 million people. To sum up all the studies of sleep duration and cardiovascular disease, every one hour a night decrease in sleep below the seven- to eight-hour threshold is associated with 6 percent higher risk of
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