The Sleep Blues: Is your computer screen keeping you awake?

Blue light at night can lead to an unproductive day.By Dr. John

In 1893, Nikoli Tesla lit up the night at the Columbian Exposition in Chicago.  His inventions in alternating electric current, together with Edison’s work on filaments, allowed us to end night at will.  Now ubiquitous, artificial lighting disrupts sleep by inhibiting the production of melatonin, the light-sensitive hormone that induces sleep. As Laura Beil writes in New York Times:

Light hitting the retina suppresses the production of melatonin — and there lies the rub. In this modern world, our eyes are flooded with light well after dusk, contrary to our evolutionary programming. Scientists are just beginning to understand the potential health consequences. The disruption of circadian cycles may not just be shortchanging our sleep, they have found, but also contributing to a host of diseases.

In the computer age, we are taking the lighting revolution a step further; a step that may be giving us the Sleep Blues. While light of any wavelength can disrupt sleep, blue wavelengths, such as those emitted by the computer screen you are using, appear to be the most disruptive. Beil, quoting neurologist and sleep specialist Dr. George Brainard:

An LED screen bright enough and big enough “could be giving you an alert stimulus at a time that will frustrate your body’s ability to go to sleep later,” said Dr. Brainard. “When you turn it off, it doesn’t mean that instantly the alerting effects go away. There’s an underlying biology that’s stimulated.

Incandescent bulbs, which produce more red wavelengths, appear to inhibit melatonin production less than the blue wavelengths given off by LED monitors and energy-efficient bulbs. Thus, if you enjoy bedtime reading but are having a hard time going to sleep, an “old fashioned” bedside lamp and a print book may be your best choice.

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The end of night

Columbian Exposition in Chicago, 1893 - the dawn of the age of light. Image: PBS.orgOver 60 million Americans have problems sleeping. While insomnia has many causes, one is the use of electric lighting.  Our circadian rhythms developed from the 24-hour rotation of the Earth. At the end of the day, the slowly fading sunlight allowed the brains of our hominid ancestors to prepare for sleep. Around 1 million years ago, hominids began to use fire and congregate around campfires for warmth and safety. Socialization increased. Eventually cooking developed and led to further brain evolution.

The first lamps, made from moss or other plant material and animal fat placed in a natural stone recesses, are tens of thousands of years old. Portable lamps fueled by animal fat, and later oil, were carried by Cro-Magnon into the deep recesses of the Lascaux and Altamira caves where they painted remarkable images of ice age fauna 13,000-18,000 years ago.

First used around 400 AD, candles were an important form of lighting for 1,500 years until the development of gas lighting at the end of the eighteenth century. As noted in A History of Light and Lighting, candles could be linked together to create a spectacle:

In 1761, at the coronation of George III, groups of 3000 candles were connected together with threads of gun cotton, and lit in half a minute. Those clustered below were showered with hot wax and burning thread.

Campfires, oil lamps, candles and gas lamps cast a dim light and

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