Pull open the curtains and flip your internal switch. Taking in some sunlight soon after you rise helps set your body’s internal clock, called circadian rhythm, so it’s easier to get to sleep at night, says James B. Maas, Ph.D., author of Sleep for Success! “Don’t keep lights too dim or low in your house,” he advises. Interior light helps get you going, but ultimately it’s outside light that’s best -- even on a cloudy day. Natural light is the most powerful watchdog of our biological clock, which regulates when we feel sleepy and when we feel alert, according to the National Sleep Foundation. If natural light is hard to come by, a light therapy box can simulate bright sunshine, especially during the short winter days when there’s limited precious daylight.