See this post and discussion from 5 years ago. I saw someone wearing red goggles at an LW meetup years ago.

EDIT: Even if this has been discussed before, I still read and enjoyed your post, and it contained new info. I think sleep optimization is important - somebody should be keeping me informed of any new research. ;)

I knew about melatonin and red/blue light from reading people in this community. I also had a vague understanding that circadian rhythms controlled falling asleep and were based on light, but I don't think I'd seen things spelled out as clearly as they are here. Thank you for putting this together and I do look forward to the rest of your series.