Exposure to the light of white LED bulbs suppresses melatonin five times more than exposure to the light of high-pressure sodium bulbs that emit an orange-yellow light, according to a new international study – that includes University of Haifa Prof. Abraham Haim.

Melatonin is a compound that adjusts our biological clock and is known for its anti-oxidant and anti-cancerous properties.

Now, Prof. Haim and his colleagues taking part in the study are calling for regulations and rules for the pollution stemming from artificial light at night.

The study, titled “Limiting the impact of light pollution on human health, environment and stellar visibility” was recently published in the Journal of Environmental Management. The researchers investigated the influence of different types of bulbs on light pollution and the suppression of melatonin.

It is already known that ‘white’ artificial light suppresses the production of melatonin in the brain’s pineal gland. Also known is the fact that suppressing the production of melatonin, which is responsible, among other things, for the regulation of our biological clock, causes behavior disruptions and health problems.

In earlier studies on the effects of artificial light, Prof. Haim, head of the Center for Interdisciplinary Chronobiological Research at the University of Haifa, linked artificial light to obesity and cancer.

In this latest study, conducted by astronomers, physicists and biologists from ISTIL- Light Polution Science and Technology Institute in Italy, the National Geophysical Data Center 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 and mall lighting.

The researchers suggest limiting the use of white light and using only the amount of light needed for a task.

As a first step in Israel, the Standards Institution of Israel should obligate bulb importers to state clearly on their packaging what wavelengths are produced by each bulb. If wavelength indeed influences melatonin production, this is information that needs to be brought to the public’s attention, so consumers can decide whether to buy this lighting or not, Prof. Haim says.