LED lights affect melatonin levels

THE increasing popularity of light-emitting diode (LED) lights might have a downside for human health, researchers say.

It has been known that ‘white’ artificial light reduces melatonin production in the pineal gland.

However, researchers have now quantified for the first time the degree of suppression depending on a person’s exposure to different light sources.

The multi-country study compared high pressure sodium (HPS) bulbs, which give off an orange-yellow light and have been used in street lighting, with ‘white’ light bulbs that actually give off blue light.

Researchers found that white-light metal halide bulbs, which are often used in stadium lighting, suppress melatonin at a rate more than three times greater than the HPS bulb, while white LED bulbs suppress melatonin at five times the rate of the HPS bulb.

Incandescent bulbs suppress melatonin at only 2.5 times the rate of HPS bulbs.