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Another important aspect to aging beautifully: lolling in bed. "Lack of sleep has been shown to raise levels of cortisol and glucose, causing health problems such as hypertension and type II diabetes, which make you age much more quickly," says James Maas, PhD, professor of psychology at Cornell University and author of Power Sleep, who recommends 7.5 to 8.5 hours. "And though we used to think that lying in bed made us slothful, in fact sleep is the best diet there is." Research has shown that compared with people who sleep eight hours a night, those getting five hours have 15 percent lower levels of the appetite-suppressing hormone leptin and 15 percent higher levels of hunger-increasing ghrelin. "You wake up starving for complex carbohydrates," says Maas. But sleep deprivation does more than wreak havoc on your body—its effects are written all over your face. .
"Skin cells turn over more quickly when you sleep," says Jeanine Downie, MD, director of Image Dermatology in Montclair, New Jersey, and coauthor of Beautiful Skin of Color. "If you don't get enough sleep, your skin won't renew itself and will start looking dull—especially as you age, when cell turnover is slowing down." Skin temperature also rises when you sleep, allowing topical treatments to penetrate the skin more effectively than they do during the day. And there's the common badge of fatigue: dark circles. While puffiness is determined by genetics, shadows are often aggravated by lack of sleep, which can cause some blood to seep from the tiny capillaries beneath the thin skin under your eyes.