[perishabledave]

Slightly aside, but is there any evidence that the warmth of the light effects sleep? The cited paper compares a light emitting device to a book, which would not be the same as f.lux and this.

Not trying to dismiss this. I'd genuinely like to know as I'm often on my computer late at night.

[xresonance]

Yes, and plenty to read on the subject. Look around for blue light and sleep / circadian rhythm / melatonin production.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2831986/