Blue light from artificial sources signals daytime to the body, interfering with melatonin production and circadian rhythm.

“the more blue your light is the worse in terms of melatonin which is not good news for most fluorescence most LEDs I see in the houses you can tell when you walk into a house like this guys you walk in and you just think oh this light sucks it's horrible even an LED that's doing a more amber light is going to be better an incandescent doing amber light is better a candle is better than that and even better than that is a red incandescent bulb but clearly blue LEDs blue fluorescence these the more blue they have in them at night the more inhibition of your melatonin you're going to create”