Autumn brings a dramatic reduction in the amount and intensity of natural sunlight. Those suspectible to Seasonal Affective Disorder (SAD), even in its more common, milder form, gradually develop a depressive syndrome characterized by feelings of gloom and lethargy, decreased interest in normal activities, increased desire to sleep and trouble getting up in the morning, and often increased cravings for carbohydrates, which can promote weight gain (and a vicious cycle of further depression). Those who have little time to get outdoors during the daylight hours may develop this syndrome at any time of the year, but for the most people the symptoms become noticeable by the end of October (in the Northern hemisphere).
Over more than four decades, light treatment with a portable lightbox has come to be recognized as the most effective and least expensive way to treat this problem. The feature article in the October 1998 issue of the Archives of General Psychiatry states unequivocally the light, as an antidepressant, "is as effective as drugs, perhaps more so." Light has also been demonstrated to be effective for treating many sleep problems, jet lag, shift-work adjustment, and the agitation that often accompanies Alzheimer's disease. It has been used by NASA to help astronauts regulate their sleep/wake cycles in space. There is also solid research demonstrating the effectiveness of light treatment for people suffering from premenstrual disorders, attention probelms, and alcoholism.
A state-of-the-art lightbox is designed to simulate the natural daylight exposure of being outdoors on a Spring morning; it delivers 10,000 lux (lux is a standard measure of light) at a comfortable distance. A lightbox can generate enormously intense light because it containts special tubes (with twice the surface area of ordinary tubes) powered by electronic ballasts. It should be relatively compact, lightweight, and energy efficient, consuming no more energy (and much less heat) than an ordinary reading lamp. A lightbox should be used daily for 15-30 minutes, generally in the morning, throughout the period of time that the user is usually symptomatic. You simply sit in front of a lightbox while reading or eating, allowing your eyes to be exposed to the light without staring at it. Most people notice the antidepressant benefits within a few days.
Humans have an internal time-keeping mechanism, and natural daylight sets and resets it daily. Whenever this biological clock gets out of sync with the realities of life, or there is not enough natural light, bright artificial light can be used as a corrective measure to advance or delay it, as needed. Melatonin plays a role in this process, since the onset of darkness promotes the secretion of this hormone and bright light stops its production. Neurotransmitters, such as seratonin and dopamine, which play a central role in regulating mood, are also involved, but the exact mechanisms of the therapeutic action of light treatment are not yet fully understood.
Learn more about seasonal affective disorder