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The Dark Side of Night

In humans as with all mammals, your biological clock resides in the suprachiasmatic nucleus of your brain (SCN), which is part of your hypothalamus. Based on signals of light and darkness, your SCN tells your pineal gland2 when it's time to secrete melatonin.

Light comes in through your eyes and travels up your optic nerves to the SCN, which is exquisitely sensitive to cycles of light and darkness.

When you turn on a light at night, you immediately send your brain misinformation about the light-dark cycle. The only thing your brain interprets light to be is day. Believing daytime has arrived, your biological clock instructs your pineal gland to immediately cease its production of melatonin.

Whether you have the light on for an hour or for just a second, the effect is the same — and your melatonin pump doesn't turn back on when you flip the light back off.

Since humans evolved in the glow of firelight, the yellow, orange and red wavelengths don't suppress melatonin production the way white and blue wavelengths do. In fact, the range of light that inhibits melatonin is fairly narrow — 460 to 480 nm*. If you want to protect your melatonin, when the sun goes down you would shift to a low wattage bulb with yellow, orange, or red light. Dr. Reiter suggests using a salt lamp illuminated by a 5-watt bulb in this color range.

http://articles.mercola.com/sites/articles/archive/2013/03/19/melatonin-benefits.aspx

http://tinyurl.com/28qjg3