Most Women know that nothing kills a good complexion like a bad night's slumber; there's a reason, after all, that it's called beauty sleep. If that's not motivation enough to keep up with your nightly shut-eye, here's another: doctors are learning that poor sleep habits may make women more vulnerable than men to heart disease and diabetes.
Are men and women so different physiologically that they react differently to troubled sleep patterns? Or are men protected somehow from the health effects of poor sleep? To find out, Dr. Edward Suarez at Duke University gathered 210 healthy men and women and asked them detailed questions about their sleep habits--including how long it took them to fall asleep, how many hours they had slumbered in the past month, whether they slept through the night and if they felt drowsy during the day. Then he recorded their levels of cholesterol, insulin, glucose, a clotting agent known as fibrinogen, inflammatory proteins that contribute to heart disease, and insulin resistance (the precursor to diabetes). Since emotional factors can affect sleep as well, he also assessed each subject's levels of depression, hostility and anger, using standard psychological questionnaires.
What Suarez uncovered was a consistent association between poor sleep and higher levels of the risk factors for heart disease and diabetes--but only among the women. Men who had trouble falling asleep or reported interrupted sleep did not show higher levels of the risk factors and therefore had reduced chances of developing the illnesses. "I kept trying to disprove the findings," Suarez says. "I put in age, but age did not do anything to destroy the results. I put in race because blacks often report worse sleep than whites, but nothing happened." Smoking and, for women, menstrual status did not eliminate the gender gap either.
The results, published in the journal Brain, Behavior and Immunity, are among the first to link poor sleep to such a wide array of physiological changes. While he cannot fully explain why men and women are affected differently, Suarez believes that testosterone could play a role. In his study, men reporting the most difficulty sleeping also had the highest levels of testosterone, which is known to reduce levels of heart-damaging inflammatory proteins. So, he speculates, while testosterone may trigger sleep problems, it may also blunt some of the physiological changes that can raise the risk of heart disease and diabetes.
Suarez's study stops short of establishing that a woman can reduce her risk for these conditions just by changing her sleep pattern, but it should galvanize women to pay more attention to the time they spend in bed. "I don't think we have to wait 20, 30 or 40 years to start intervention," says Dr. Phyllis Zee, director of the sleep-disorders center at Northwestern University. "Just as we teach patients to eat well and exercise for their health, we should be telling them to sleep well." In other words, for women, a good night's rest is far more than just beauty sleep.