How Much Sleep Do You Really Need?(How Much Sleep Do You Really Need? )

The term sleep disorder may suggest someone tossing and turning all night, but lying awake for hours with insomnia is just one example of many conditions that affect how you sleep and function during the day. In fact, you can have a sleep disorder and not even know it.

How many hours should you sleep?

There's no normal number of hours that quantifies a good sleep, just like there's no normal shoe size. Most adults need seven to nine hours a night; others manage just fine with six. It's even possible to get too much sleep, since spending excess time in bed can be a sign of another health problem, such as depression or chronic fatigue syndrome.

A 2007 British study found that people who slept the same amount of time (seven hours) each night lived longer, on average, than people who adjusted their schedules to either add or subtract hours from their nightly slumber. Finding your own ideal sleep/wake cycle—and staying consistent—is key to healthy sleep, agrees Carol Ash, D.O., medical director of the Sleep for Life center in Hillsborough, N.J.

Don't sell yourself short

That doesn't mean you can shave off hours of much needed rest without consequence: In a different study, the same British scientists also found that people who are consistently sleep deprived (defined as sleeping five hours or less a night) are at greater risk for high blood pressure and cardiovascular problems—especially women.

Insufficient sleep also raises your risk for obesity, diabetes, depression, alcoholism, and automobile accidents. Plus, a 2007 University of California-Berkeley study confirmed the obvious: Sleep deprivation directly affects areas of the brain that deal with mood and concentration, leaving tired people grumpy, overly emotional, and unable to focus.

Consider quality and quantity

For all these reasons, doctors need to look at both the quantity and the quality of sleep to detect a problem. And when it comes to sleep quality, problems aren't always obvious to patients themselves: An insomniac who lies awake at night can easily tell that something is wrong, for example, but someone with sleep apnea who repeatedly stops breathing in his sleep might have no idea there's a problem.

The most telling sign of a disorder is how you feel during the day. If you generally wake up alert and refreshed, you're a healthy sleeper. If you chronically wake up sleepy, irritable, and unfocused—and stay that way throughout the day—you may have a sleep disorder, no matter how much time you spend in bed.

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