Wearing sunglasses during the day may prevent adequate bright sunlight from reaching the eyes, potentially disrupting circadian rhythms.

“I do not wear sunglasses when I do my morning sunlight viewing to set my circadian rhythm and I suggest that you do the same”

“I think a lot of people out there maybe you are gonna put sunglasses on first thing in the morning and never get good bright sunlight in their eyes some of the day”

“But here's the trick. Here, in California a lot of people make this mistake, but even in London, it happens despite cloudy day, people put shades on in the morning. Don't do that. I know it looks good. But don't. Let that natural light penetrate your eye. There's a retinal mechanism that goes through to your thalamus that then goes through the hypothalamus that regulates your circadian clock. You need that light penetration.”