The body’s natural sleep rhythm is governed by the circadian clock, which is sensitive to light. In the daytime, the brain is stimulated by blue light, making us more alert. At night, however, blue light suppresses the production of melatonin, the hormone that makes us feel sleepy. According to a study published in the Journal of Biological and Medical Rhythm Research, blue light disrupts the production of melatonin, which can prevent you from sleeping.
Melatonin levels should naturally rise in our bodies approximately two hours before sleep. The rise in melatonin directly contributes to the drowsiness that signals you’re ready for sleep. But if you’re exposed to blue light, melatonin production can get disrupted, making it harder to fall asleep or stay asleep. Blue light exposure can also lead to poorer quality sleep, as it can reduce the time spent in deep sleep.