Effects of Sleep Loss
As many people try to fit more activities and chores into every minute of every day, they often steal time from their sleepoperating on the "you snooze, you lose" principle. But the real loss may come if you don't get enough sleep. While it's long been known that getting plenty of shut-eye is important for your ability to concentrate and be productive, only recently have researchers discovered just how hazardous to your health insufficient sleep can be.
Besides increasing your risk of having an accident behind the wheel or just about anywhere else, chronically short-changing yourself of sleep can affect you from head to toe in potentially serious ways: "The cumulative effects of sleep loss and sleep disorders represent an under-recognized public health problem and have been associated with a wide range of health consequences including an increased risk of
- heart attack, and
- stroke," the Institute of Medicine noted in a 2006 report.
And yet, many people in the United States continue to skimp on sleep: Adults who work 30 or more hours per week get an average of 6 hours and 40 minutes of shut-eye per night during the work-week, according to the latest poll by the National Sleep Foundation (NOF). This is considerably less than the 7 1/2 to 8 1/2 hours most adults need nightly to feel and function at their best, notes Richard J. Schwab, M.D., co-director of the Penn Center for Sleep Disorders at the University of Pennsylvania in Philadelphia. At first, this may not seem like much of a difference but short-changing yourself of just one hour of sleep per night adds up quicklyto the equivalent of losing an entire night's sleep after seven nights.
"A lot of people have self-inflicted sleep problemsit's their lifestyle or their job or their commuting that's to blame," says Meir Kryger, M.D., director of research and education at Gaylord Sleep Medicine in Wallingford, Connecticut, and chairman of the board of the NOF. Indeed, the NOF poll found that many people are spending longer hours at work and often taking work home with them, which is part of the reason they're sleeping less than they should.
Hidden Hazards From Head to Toe
How does sleep loss harm you? For starters, inadequate sleep can affect your memory, learning, and thinking abilities, as well as the speed at which you execute mentally challenging tasks. What's more, research at the Walter Reed Army Institute of Research found that sleep deprivation can affect your moral judgmentabout the "appropriateness" of certain courses of action in different situationsby impairing your ability to integrate emotions and thought in guiding you to do the right thing.
In addition, chronic sleep loss is causing one in five people to have sex less often or to lose interest in sex simply because they are so tired, according to the latest NOF poll. And too little sleep can trigger headaches, depression, anxiety, or irritability in those who are susceptible to these conditions.
Short-changing yourself of adequate sleep can also compromise your immune function, including your body's response to vaccinations. And it can affect your experience of pain: Research at the Sleep Disorders and Research Center at the Henry Ford Health System in Detroit found that losing 4 hours of sleep substantially increases a person's sensitivity to pain the following day. "Inadequate sleep increases sensitivity to pain, which in turn disrupts sleep," setting up a vicious cycle, notes Gregory Belenky, M.D., research professor and director of the sleep and performance research center at Washington State University in Spokane.
Over the long-term, the consequences of chronic sleep loss may be even more serious. Researchers have discovered that getting only 4 or 5 hours of slumber per nightwhat's considered partial sleep deprivationcan increase a person's risk of developing chronic inflammation or diabetes (both of which can increase the risk of heart disease), as well as experiencing an acceleration of the aging process.
"When you don't sleep enough, your body isn't as responsive to insulin as it should be, which can lead to insulin resistance and type 2 diabetes," explains Dr. Kryger, author of A Woman's Guide to Sleep Disorders. Sleep loss can also exacerbate diabetes: In a study at the University of Chicago, researchers found that short or poor quality sleep is associated with reduced control of blood-sugar levelsbased on measures of hemoglobin A1cin African American adults with type 2 diabetes.
While the occasional poor night of sleep isn't likely to harm you, making a habit of getting too little sleep will, though it can take a while for the effects to kick in. "Just as you don't get atherosclerotic vascular disease by eating prime rib onceyou get it by eating a high-fat diet over timechronic sleep restriction over days and weeks and months is what alters glucose metabolism, nudging it toward the pre-diabetic end of the spectrum," says Dr. Belenky. "And sleep loss leads to an increased inflammatory response, which damages the arteries in the brain, heart, and kidneys over time."
Indeed, research at Columbia University in New York City suggests that regularly cheating yourself of sleepso that you clock five or fewer hours of shut-eye per nightcan double your risk of developing hypertension over a ten-year period. "When you sleep, your blood pressure and heart rate normally dip by about 10 to 20 percent," explains lead author James Gangwisch, Ph.D., an assistant professor of psychiatry at Columbia. "If you habitually sleep less than the optimal amount, blood pressure and heart rate actually increase over 24 hours, which puts additional strain on the cardiovascular system. Over time, this can gradually reset the entire cardiovascular system so that it operates at an elevated pressure all the time."
Meanwhile, mounting evidence suggests that insufficient sleep can increase your chances of gaining weight. In a study at Case Western Reserve University in Cleveland, researchers found that women who habitually sleep five or fewer hours per night had a slightly higher rate of weight gain over 16 years than those who get seven hours per night. And a study at Columbia University found that people between the ages of 32 and 49 who sleep less than seven hours per night had a higher average body mass index (BMI) and were more likely to be obese than people who sleep at least seven hours.
"With too little sleep, there are changes in levels of the hormones ghrelin and leptin [both of which are key in regulating appetite and food intake]changes that cause you to eat more," Dr. Kryger explains. In fact, a recent study at the University of Chicago found that when sleep was restricted to 5 1/2 hours per night, healthy people consumed more calories and carbohydrates from snacks than they did after getting 8 1/2 hours of shut-eye per night.