(p. D6) Studies have shown that such light, especially from the blue part of the spectrum, inhibits the body’s production of melatonin, a hormone that helps people fall asleep.
. . .
Devices such as smartphones and tablets are often illuminated by light-emitting diodes, or LEDs, that tend to emit more blue light than incandescent products.
For the full story, see:
KATE GALBRAITH. “WIRED WELL; Can Orange Glasses Help You Sleep Better?” The New York Times (Tues., APRIL 7, 2015): D6.
(Note: ellipsis added.)
(Note: the online version of the story has the title “WIRED WELL; Can Orange Glasses Help You Sleep Better?”)