online.wsj.com | Article Link | Sumathi Reddy
How much sleep do you really need?
Experts generally recommend seven to nine hours a night for healthy adults. Sleep scientists say new guidelines are needed to take into account an abundance of recent research in the field and to reflect that Americans are on average sleeping less than they did in the past.
Several sleep studies have found that seven hours is the optimal amount of sleep—not eight, as was long believed—when it comes to certain cognitive and health markers, although many doctors question that conclusion.
Other recent research has shown that skimping on a full night's sleep, even by 20 minutes, impairs performance and memory the next day. And getting too much sleep—not just too little of it—is associated with health problems including diabetes, obesity and cardiovascular disease and with higher rates of death, studies show.
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