About Light: Hibernation, Seasonal Affective Disorder

by SonjaHelga on Wednesday, November 28th, 2007 | Comments Off

Morning Sun

The Morning Sunlight Photographer: Revati Upadhya

Perhaps I am a bear, or some hibernating animal underneath, for the instinct to be half asleep all winter is so strong in me. -Anne Morrow Lindbergh

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Short days, long nights, bitter temperatures, and bare landscapes. Perhaps we are all bears underneath, as the winter months have always been a time to slow down, cozy up, and settle in. Indeed, the word hibernate itself comes from the Latin hibernare, to pass the winter.

Curiously, “hibernate” was first used at the relatively late date of 1802. According to Noah Webster, it was Erasmus Darwin, grandfather of the famous “Father of Evolution,” Charles Darwin, who is credited with the word. The elder Darwin, also a scientist, no doubt observed the behavior of such hibernating animals as badgers and hedgehogs; but perhaps, as a member of the elite class, who did not have to perform manual labor outside, he noticed his own winter behavior as well.

Every mile is two in winter. – George Herbert

Science has come a long way since then, and we now know that the lack of bright light in winter can cause a life-disrupting condition known as seasonal affective disorder, or SAD. The constellation of symptoms that characterize SAD go way beyond hibernation. For an estimated half a million people around the world, winter brings feelings of misery, hopelessness and despair; fatigue and lethargy that make every daily action an effort; physical symptoms such as joint pain or stomach problems; carbohydrate cravings that lead to overeating and weight gain; and excessive sleep that does not feel restful.

Women and young people are more susceptible to SAD, which usually begins between the ages of 18 and 30. SAD occurs throughout the northern and southern hemispheres, but as, you may imagine, it is extremely rare near the equator, where days are consistently long and bright.

Just as SAD is caused by the lack of bright light, the treatment for SAD is to be in bright light. Phototherapy typically takes the form of a lightbox, a device that provides at least 2500 lux (lux is the technical measure of brightness), which is about ten times brighter than ordinary domestic lighting. The lightbox is a bank of white fluorescent lights on a metal reflector and shield with a plastic screen. Users sit two to three feet away from the box, allowing the light to shine directly through the eyes. Tinted lenses, or any device that blocks the light to the retina of the eye, should not be worn.

Go outside and play. – Mom

Other studies have shown that simply getting outside, even on a cloudy day, can be just as effective as bright artificial light. It has even been speculated that natural light is essential to our health and well being, so much so that it may be considered to be a part of the body’s nutritional needs.

Conversely, some believe that artificial light can block the benefits of certain vitamins and minerals. In his book Mega-Nutrients For Your Nerves, H.L. Hembold, M.D. describes how full-spectrum light enters the eyes, stimulates the brain, and facilitates the absorption and utilization of specific nutrients. He maintains that if some of the energy bands of the light spectrum are missing, certain vitamins and minerals are inadequately absorbed and poorly utilized.

John Ott, a pioneer in the relatively new field of photobiology, stated that “by deliberately screening out supposedly harmful traces of atmospheric ultraviolet with tinted windows, sunglasses, suntan lotions and the like” we may be making ourselves sick from what he termed “malillumination” which he thought of as a sort of malnutrition. (Quote from an article in the San Francisco Chronicle, September, 1987)

These are daring suggestions indeed: just ask the light-bulb lobby or doctors who treat skin cancer. Yet they are intriguing and suggest the need for further inquiry. Certainly we know how good it feels to sunbathe on a beach and how tired we feel on a classic rainy day (and how lucky we feel when we get away to someplace warm and sunny in the middle of winter!). Look for future Rebuild Your Vision Blog Postings on how different types of lighting affect your eyes. And until then, get into winter sports and get outside and enjoy!