Melatonin levels affected by LED lights
20 September 2011
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 production of melatonin - a hormone involved in regulating the 'body clock'.
However, researchers have now quantified for the first time the degree of suppression of melatonin depending on a person’s exposure to different light sources.
The multi-country study compared white light bulbs that actually give off blue light with high pressure sodium (HPS) bulbs, which give off an orange-yellow light and have been used in street lighting.
Researchers found that white-light metal halide bulbs, which are often used in stadium lighting, suppress melatonin at a rate more than 3 times greater than HPS bulbs, while white LED bulbs suppress melatonin at 5 times the rate of HPS bulbs.
Incandescent bulbs suppress melatonin at only 2.5 times the rate of HPS bulbs.
Melatonin, which is produced by the pineal gland in the centre of the brain, is important for adjusting the biological clock, and has documented antioxidant and anti-cancer properties, the researchers said (Journal of Environmental Management 2011; 92: 2714-22).
The current move to white lamps will likely increase melatonin suppression in humans and animals, making night-time lighting a public health issue warranting regulation like classic pollutants, they warned.
Last Reviewed: 23 September 2011
- 1. Falchi F, Cinzano P, Elvidge CD, et al. Limiting the impact of light pollution on human health, environment and stellar visibility. J Environ Manage 2011; 92: 2714-22. [Epub 2011 Jul 13]. doi:10.1016/j.jenvman.2011.06.029. http://www.sciencedirect.com/science/article/pii/S030147971100226X (accessed Sep 2011).
