Bright light, particularly blue light, suppresses melatonin production; high exposure during the day and minimal exposure at night is beneficial.

“Right, so this is. - Right. - Right. - Anyway, this is the major source of melatonin in your body. - So light comes in to my eye. - Yes. - Passed off to the suprachiasmatic nucleus essentially, not the light itself, but the signal representing the light. - Sure. - Then the SCN, the suprachiasmatic nucleus can impact the melatonin system. - Right. - Via the pineal? - Right, the way this is seen is that, if you were to measure your melatonin level over the course of the day, if you could do this hour by hour, you'd see that it's really low during the day, very high at night. But if you get up in the middle of the night and go to the bathroom and turn on the bright full fluorescent light, your melatonin level is slammed to the floor.”

“Any light, provided it's bright enough, will shut down melatonin production.”

“that bright light exposure will absolutely quash, it will eliminate, any melatonin that happens to be circulating in your brain and body.”

“as little as 15 seconds of bright light in the evening I think CH Chuck Zer laboratory at Harvard Medical School showed can quash melatonin in the evening”

“Light inhibits melatonin powerfully. ... So every cell in your body actually knows external day length and therefore time of year by way of the duration of the melatonin signal.”

“The other thing to understand is the very firmly established fact, which is that light powerfully inhibits melatonin. If you wake up in the middle of the night and you go into the bathroom and you flip on the lights and those are very bright overhead fluorescent lights, your melatonin levels, which would ordinarily be quite high in the middle of the night because you've been eyes closed in the dark presumably, will immediately plummet to near zero or zero.”

“even just a brief flash of light in the middle of the night can you quash your melatonin”

“it's been shown that light inhibits the production of melatonin um particularly blue light because it's more uh bright light so you should try to avoid too much light at night”

“So bright light shuts off melatonin, the blue light, right? Yeah. You want a lot of it during the day, and then you don't want too much of it at night.”

“You brought up a lot of really important points for, one, talking about avoiding bright lights or blue light exposure in the evenings. And some people may not be familiar with why that is. So a key driver of the body's circadian rhythms is melatonin, which people probably have heard of. It's a sleepiness hormone. But it rises towards the evening because blue light inhibits it.”

“bright light exposure can inhibit that so it can hasten the clearance of the melatonin”