The article is saying "cool it and dim it" but I think they mean to say "warm it and dim it". They suggest the temperature should not be above 3000 kelvin.
I posted the initial reference as an entry point to follow literature on potential effects of illumination color temperature on human sleep, or perhaps circadian rhythms, through action on a hormone known to be critically involved in sleep. I didn't suggest it was the end of the story. My post was on topic and it contributed to the discussion.
Would be glad to review data you think interesting.
http://onlinelibrary.wiley.com/doi/10.1111/apha.12552/abstra...
http://proceedings.spiedigitallibrary.org/proceeding.aspx?ar...
http://www.sciencedirect.com/science/article/pii/S0304394008...
The second article covers how bright light can be without being painful, and doesn't mention sleep or melatonin. Or at least the abstract does, again the article is paywalled, but at least it involves 500 participants.
The third study only covers 12 participants. I'll grant there may be thousands of these studies, each with a handful of subjects. Is there some statistical way to stitch the results together in any meaningful fashion - or would that just result in a low p-value?