A new study has found that exposure to white LED bulbs suppresses our brain's production of melatonin that is responsible, among other things, for the regulation of our biological clock, more than exposure to the bulbs emitting orange-yellow light.

In this study, conducted by astronomers, physicists and biologists from ISTIL- Light Pollution Science and Technology Institute in Italy, the National Geophysical Data Centre in Boulder, Colorado, and the University of Haifa, researchers for the first time examined the differences in melatonin suppression in a various types of light bulbs, primarily those used for outdoor illumination, such as streetlights, road lighting, mall lighting and the like.

They found that the metal halide bulb, which gives off a white light and is used for stadium lighting, among other uses, suppresses melatonin at a rate more than 3 times greater than the high-pressure sodium HPS bulb that gives off orange-yellow light.

Also the LED bulb, which also gives off a white light, was found suppressing melatonin at a rate more than 5 times higher than the HPS bulb.

The study was recently published in the Journal of Environmental Management.