We mark our days by sunlight, with special receptors in our eyes that respond to light and help reset our body clocks each day. This man can’t see, but is still a circadian wiz.
"circadian rhythms"
Sleeping with even a little bit of light isn’t good for your health, study shows
The findings tie into a broader body of evidence that indicates being exposed to light at night may be harmful in a variety of ways and could predispose people to chronic diseases.