Tossing and turning at night? You're not alone. Nearly half of adults in the U.S. say they rarely -- or never -- get a good night's sleep, according to a poll by the National Sleep Foundation. That can cause a slew of health problems, including a bigger waistline. Dr. Charles Czeisler, a sleep researcher at Harvard Medical School, said in a 2011 interview with NPR that shorter sleep duration causes a change in the hormones that regulate appetite and the metabolism of sugar. That change makes you crave more food, especially carbs.