You’ve tried all the tricks: warm milk, a dark room, a regular bedtime. But nothing seems to alleviate the tossing and turning—and you need sleep. The culprit, it appears, could be cold feet. Thermoregulation (the body’s heat distribution system) is linked to sleep cycles, and research shows that when your body gets ready for sleep, it pumps blood to your hands and toes. Warming your feet with socks or a hot-water bottle can help trigger drowsiness because it mimics the body’s natural sleep-prep pattern.