So viewing bright light in the late evening hours and nighttime hours is really not good for your sleep quality and your ability to fall and stay asleep . So for most people , a simple rule of thumb is going to be avoid bright artificial lights of all colors and in particular overhead bright artificial lights between the hours of 10 p.m. and 4 a.m. That's right between 10 p.m. and 4 a.m. Avoid those bright artificial lights as much as possible . Use only as much light as is absolutely necessary .
So candlelight is fine , of course , be cautious with open flame , but candlelight is fine , moonlight is fine . Dimming , artificial lights is fine provided they're dimmed way , way down and again , try and avoid using overhead artificial lights . The absolute worst lights are going to be overhead fluorescent lights of the sort that you would have in the supermarket or uh that you would see at a gas station or something of that sort .
And if you really want to optimize your sleep wake cycles , I suppose you could also do the opposite throughout the day . You could really emphasize the use of bright artificial lights and sunlight that comes from above . And of course , sunlight always comes from above .
So this is a beautiful adaptive mechanism that allows these cells to respond to overhead light from sunlight in the early part of the day and throughout the day . But in the evening , if you have bright artificial lights on , and those bright artificial lights are overhead lights , it's going to more closely mimic what sunlight does in the evening time . And that turns out to be a bad thing if your goal is to eventually go to sleep .
If you are going to use light at night . And most people do , I would encourage you to use as little artificial light as is required to carry out the activities you need to require safely . That could be studying .
