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On the sofa, in front of the TV. On the train, surrounded by fellow commuters. In the movie theater, before the film begins. If you can't stay awake in any -- or all -- of these places, it's a good bet you're sleep-deprived. This lack of shut-eye does more than make you chronically grouchy; it elevates your risk of high blood pressure and obesity. And now there's a whole new reason to put an end to your sleep starvation: Skimping on rest could increase your chances of getting type 2 diabetes, a disease once believed to be caused primarily by being overweight. In fact, just three consecutive nights of inadequate sleep can elevate a person's risk to a degree roughly equivalent to gaining 20 to 30 pounds, according to a 2007 study at the University of Chicago.
"Sleep may be as important as exercise or diet when it comes to developing diabetes," says Eve Van Cauter, MD, a professor of medicine and the senior author of the study. This revelation backs up previous research from Yale and the New England Research Institutes, which showed that people who clock six hours or less of sleep a night are twice as likely to develop diabetes in their lifetime as those who snooze seven hours. Translation? If you're not getting enough rest -- even if you're slim and fit -- you're putting your health in serious jeopardy.
Here's what we know: Diabetes arises when the body can't properly break down blood sugar, aka glucose, leaving your cells starved for energy. One thing that greatly increases your chances of a blood-sugar malfunction is being overweight. Excess fat makes it harder for cells to properly use insulin, a hormone that helps keep glucose levels normal.
So what does sleep have to do with any of this? "When you don't get enough, your body appears to require more insulin to maintain normal glucose levels," says James Herdegen, MD, medical director of the Sleep Science Center at the University of Illinois in Chicago. "Sleep deprivation seems to alter the sympathetic nervous system -- the body's stress-control center -- and hormonal balances, all of which affects glucose regulation." Eventually, sleeplessness causes insulin-producing cells to stop working properly, elevating glucose levels and leaving you wide open to diabetes. "Adding to the problem is the fact that fatigue also jolts the sympathetic nervous system into high gear, throwing off its ability to regulate blood sugar," Dr. Cauter says. Indeed, numerous experts point out that it takes just two nights of sleeping four hours or less to temporarily disrupt the process.
Of course, there is the more familiar explanation for why fewer zzz's nudge you closer to diabetes: The less you sleep, the more likely you are to overeat. When you're tired, your body produces extra ghrelin, a hormone that stimulates appetite, and decreases its production of leptin, a hormone that flips on the "I'm full" switch in your brain. Not only do you wind up wanting to eat a lot, but you also crave more calories and carbohydrates to get a quick energy boost. (A study in the Annals of Internal Medicine found that when healthy people got just eight hours of shut-eye in a 48-hour period, their lowered leptin and raised ghrelin levels upped their appetite for unhealthy high-carb, high-calorie foods by as much as 45 percent.)
Sleep scarcity poses the greatest danger to those who are already predisposed to diabetes, such as anyone who's overweight or has a family history of the disease. "For those people, a few nights of poor sleep can push them over the edge," Dr. Cauter says. But even if your genes (or jeans) don't indicate danger, you're not off the hook: In the past 49 years, Americans have shaved a full hour off their nightly sleep schedule, moving from approximately eight hours in 1960, according to the American Cancer Society, to about seven hours today, finds the National Sleep Foundation. Furthermore, the organization reported that 67 percent of women regularly miss out on a good night's rest, possibly doubling their chances of getting diabetes, says Kenneth Snow, MD, acting director of the Adult Diabetes Program at Harvard Medical School's Joslin Diabetes Center.
The first step to lowering your risk is figuring out the ideal amount of shut-eye you need. "Contrary to popular belief, eight hours isn't always the gold standard," Dr. Herdegen says. Anywhere from seven and a half to nine hours may be your sweet spot, depending on factors like genetics and age. For example, kids and teens need more than thirtysomethings but less than seniors. Your fitness level also plays a role. "Doing a 30-minute workout three times a week will likely improve the quality of your sleep, leaving you more refreshed with the same amount," Dr. Herdegen says. The general rule: If you feel rested when you wake up -- regardless of hours asleep -- that's a good marker that you're getting enough sleep. However, "if you feel sluggish during the day, you're putting yourself at risk," says Sam Fleishman, MD, medical director of the Sleep Center at Cape Fear Valley Health System in Fayetteville, North Carolina.
Fortunately, the sleep-diabetes connection is reversible. Move your bedtime forward by 45, 30, or just 15 minutes each night. After about four or five days, you'll find yourself waking up a few minutes before the alarm goes off -- that's your magic number. Still groggy? "Squeeze in extra sleep by napping," Dr. Herdegen says. "Be sure your nap is no more than 30 or 40 minutes long and you take it at least six hours before bedtime. Otherwise, it'll be harder to fall asleep that night."
And keep in mind that while your body can recover from short periods of sleep deprivation, it's harder to bounce back if the problem is chronic. "The more sleep you cut out over the long term, the harder it becomes to properly catch up on every hour you've lost," Dr. Herdegen says. "Your body interprets that sleep deficit as a constant stressor, and the chance you'll get diabetes grows." The best avoidance strategy: Sleep well, eat healthfully, and keep on exercising.
By Holly Pevzner
Need help getting to -- and staying in -- dreamland? We've got 8 easy ways to transform your sleep habits.1. Redecorate
"Push the head of your bed flush to the wall," says Carol Ash, DO, medical director of the Sleep for Life Program in Hillsborough, New Jersey. "This increases your unconscious sense of security, which promotes restful sleep."2. Get Sweaty
"Exercising in the morning helps you drift off faster and improves sleep quality," says Sam Fleishman, MD, medical director of the Sleep Center at Cape Fear Valley Health System in Fayetteville, North Carolina. "If you can't do an a.m. workout, get it in at least two to three hours before bed." The reason? Exercise raises body temperature; several hours later it dips back. Your body needs to cool down to go to sleep.
Eat a snack that's caffeine- and alcohol-free, not too spicy, and easy to digest, like apple slices with peanut butter. Noshing about two hours before turning in staves off middle-of-the-night hunger pangs but won't overstimulate your digestive system, which could keep you up.4. Shut Down
Thirty minutes before bed, say no to the TV and computer. Their pulsing lights signal the brain to stay awake.5. Enter Darkness
Pull the blackout curtains tight! Even a minimal amount of light can decrease sleep quality and alter your normal sleep rhythm.6. Cuddle Up
Got a partner who doesn't snore? Ask to be spooned. "It's a very comforting position to be in to help you relax," Dr. Ash says.7. Do Something Different
"If you've been tossing and turning for 20 minutes, get out of bed," Dr. Ash says. You don't want to start associating bed with frustration. "I encourage patients to have a sleep kit with items they can use in the middle of the night to help them relax, like knitting or catalogs to thumb through."8. Wake to Music
While it's best to awaken naturally, if you can't, find a way to start the day that's not too jarring. "Try swapping your buzzer-sounding alarm clock for one that plays music instead. If it doesn't do the trick, increase the volume or try a clock that beeps," says Shelby Harris, an assistant professor of neurology and psychology at Albert Einstein College of Medicine in the Bronx.
By Cary Barbor
Keep an eye on these factors that also contribute to the disease, says Todd Brown, MD, PhD, an assistant professor of medicine in the division of endocrinology and metabolism at Johns Hopkins University in Baltimore.Extra weight
Being overweight is the number-one risk factor for diabetes. Dropping 5 percent to 7 percent of your body weight can turn your future around.Belly fat
Break out the tape measure. If your waist is more than 32 inches, your chance of developing diabetes increases.Race
African Americans, Native Americans, and Hispanics are genetically predisposed to insulin resistance. South Asians are at higher risk too.Family history
Having an immediate family member with the disease ups your odds.Gestational diabetes
Developing this form of diabetes while pregnant increases the likelihood you'll wind up with type 2 after the baby is born.Prediabetes
This is when your blood glucose levels are high, just not high enough to be diagnosed as diabetes -- yet. To stay healthy, everyone should be tested for high blood sugar after age 45 -- earlier if you have other known risk factors.Medications
Immunosuppressive drugs, steroids, and some depression treatments can cause your body to become insulin-resistant, increasing your chance of diabetes. Ask your doctor whether your regimen should make you extra vigilant.
Talk to your doctor if you experience any of these red flags for type 2 diabetes. A simple blood-sugar test is the only way to find out if you have the disease.
Originally published in FITNESS magazine, March 2009.