Does LED lighting at night have bad effects? | John Wallace|
Laser Focus World A team of researchers from Israel, Italy, and
the U.S. are now saying that the light emitted by a white-light
LED suppresses melatonin in humans at a relatively high rate.
Melatonin suppression is apparently not a good thing, causing
"behavior disruptions and health problems," as noted by a
University of Haifa press release on the study. This is because
it disrupts the circadian rhythm. The researchers compared three
types of bulbs: white LEDs, metal-halide lamps (used in car
headlights and outdoor lighting), and high-pressure sodium (HPS)
lamps. Melatonin suppression is caused by blue light; HPS lamps,
with their orange-yellow hue, were the controls in the
experiment. The results showed that metal-halide lamps suppress
melatonin at a rate more than three times greater than the HPS
bulbs, while white LEDs suppress melatonin at a rate more than
five times higher than the HPS bulb. The study, titled "Limiting
the impact of light poll