Every night, two to three hours before your bedtime, a tiny gland in your brain begins to release a hormone called melatonin. Melatonin tells your body that it’s nighttime and makes you sleepy. When daylight, which is a blue light, hits the back of your eyes in the morning, your brain stops producing melatonin. You feel awake and ready to start your day. When blue light fades (and is replaced by darkness or the yellow glow of incandescent bulbs), melatonin begins to be released again. Guess what else radiates blue light? Screens.
