September 12, 2011
Science Daily/University of Haifa
Exposure to the light of 'white' LED bulbs appears to suppress melatonin five times more than exposure to the light of high pressure sodium bulbs that give off an orange-yellow light, according to new research.

"White" light bulbs that emit light at shorter wavelengths are greater suppressors of the body's production of melatonin than bulbs emitting orange-yellow light, a new international study has revealed. Melatonin is a compound that adjusts our biological clock and is known for its anti-oxidant and anti-cancerous properties.

The study investigated the influence of different types of bulbs on "light pollution" and the suppression of melatonin, with the researchers recommending several steps that should be taken to balance the need to save energy and protecting public health.

The fact that "white" artificial light (which is actually blue light on the spectrum, emitted at wavelengths of between 440-500 nanometers) suppresses the production of melatonin in the brain's pineal gland is already known. 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.
http://www.sciencedaily.com/releases/2011/09/110912092554.htm