According to Dr. Phyllis C. Zee, associate director at the Center for Sleep & Circadian Biology, Northwestern University School of Medicine, light has an enormous effect on circadian rhythms—your body’s daily physiological clock(4). Too much exposure to light before bed can keep your body from entering a restful state and may prevent you from remaining asleep for long enough. Keep lights dim at night and don’t sleep with the light on. You may even consider wearing an eye mask as one Chinese study found that earplugs and eye masks worn during sleep increases the levels of melatonin produced in the body(5). Or, you could invest in blackout curtains. These curtains are specifically designed to reduce noise by up to 40%, block out 99% of light, and help you save up to 25% on home heating and cooling costs.