How Your Morning and Nighttime Routines Affect Your Health
Why that's good: Any kind of light can suppress the secretion of melatonin, the calming hormone that brings on sleep. "The color or wavelength doesn't matter as much as people think it does," Morgenthaler says. Exposure to normal room light in the 8 hours before bedtime delayed the onset of melatonin secretion by more than an hour and a half compared with explosure to dim lighting, according to a study in the Journal of Clinical Endocrinology and Metabolism.
One more thing: You don't have to sit in darkness after the half-hour-till-bed mark. Light that's just bright enough to read by shouldn't compromise your sleep, says Morgenthaler.