Take a hot bath
Your temperature naturally dips at night, starting two hours before sleep and bottoming out at 4 a.m. or 5 a.m., according to a 1997 study conducted by New York Hospital-Cornell Medical Center. When you soak in a hot tub, your temperature rises and the rapid cool-down period immediately afterward relaxes you.
Two hours before bed, soak in the tub for 20 or 30 minutes, recommends Joyce Walsleben, PhD, associate professor at New York University School of Medicine. If you raise your temperature a degree or two with a bath, the steeper drop at bedtime is more likely to put you in a deep sleep, she says. A shower is less effective but can work, as well.