It is well known that blue light suppresses melatonin, increases cortisol and disrupts sleep. A quality red light device should not emit blue light. But there is some evidence that red light can have a minor impact on sleep if the light intensity is strong enough. I personally do have a lighter sleep when I use red light late at night. But I do have friends and clients who have noticed that their sleep stays just as deep when using red light right before going to sleep.