Humans have peak visual sensitivity to the yellow and green parts of the visible spectrum. But it is blue-white light—exactly of the sort most produced by cheap LEDs—that dominates the regulation of human circadian rhythms and other important biological cycles.
The wide-scale adoption of LEDs will reap huge energy savings, which is a good thing.
The question is, are the great energy savings compromising human health and ecosystems?
New Map Shows the Dark Side of Artificial Light at Night
More than a third of humanity cannot see the Milky Way due to light pollution, and a new wave of energy-efficient lighting could make the problem much worse
by Lee Billings
http://www.scientificamerican.com/article/new-map-shows-the-dark-side-of-artificial-light-at-night/