From: Avigayil Kadesh, NoCamels
Published January 9, 2012 08:43 AM

Light At Night Not A 'Bright' Idea

Moonlight and starlight aren't just romantic, according to a new international study with Israeli input. This natural nighttime light is also healthier than harsh artificial light — especially LED (light-emitting diodes) white light, which suppresses the brain's night time production of Melatonin needed to regulate our biological clocks, behavior and health.

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"Light is beneficial, but dark is also beneficial," says Prof. Abraham Haim, head of the Center for Interdisciplinary Chronobiological Research at the University of Haifa.

"We should live in darkness at night, but since early human evolution one of the properties humans wanted to change was the darkness. So we need to ask what type of illumination is less harmful."

That was the goal of the study, recently published in the Journal of Environmental Management by Haim and other researchers using data from astronomers, physicists and biologists at the Light Pollution Science and Technology Institute in Italy and the National Geophysical Data Center in Boulder, Colorado. Haim joined the team about a year ago.

The scientists investigated the effect of different types of outdoor lighting on light pollution and Melatonin, in order to suggest practical steps for balancing productivity, energy expenditure and public health.

Higher wavelength, higher Melatonin

White LED light (which is actually blue light on the spectrum) is emitted at short wavelengths of between 440-500 nanometers. The study showed that this type of light suppresses the body's production of Melatonin five times more than the orange-yellow light given off by traditional high-pressure sodium (HPS) bulbs. Metal halide bulbs, often used for stadium lighting, suppress Melatonin at a rate more than three times greater than the HPS bulb.

Article continues: http://nocamels.com/2012/01/white-light-at-night-isnt-bright/

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