The science: Melatonin is a chemical produced in the brain’s pineal gland at night time in order to regulate the body’s natural sleep/wake cycle. In the evening, the production of melatonin is triggered and continues throughout the rest of the dark nighttime hours that follow. When the sun comes up, its production is suppressed until the next evening when the process can repeat itself. When even a little bit of light is present in your bedroom (such as that from a window, television, or electronic device), melatonin production is partially inhibited and your circadian rhythm is disrupted (Reiter, 1991).
What you can do: Make sure that there are no visible lights in the room where you sleep. Turn off the television, ensure no lights are coming from your phone, and try to use an alarm clock that doesn’t have digital lights. Further, make sure your curtains are closed. For added light suppression, consider adding blackout curtains to your bedroom.