What is Seasonal Affective Disorder?
Seasonal Affective Disorder (S.A.D.) is a specific type of major depression, one which reoccurs at specific times of the year. The most common pattern is the onset of major depression in the fall (September through November) and abating of the symptoms in late winter to early spring (March through May). There are other people who experience periods of abnormally high or euphoric mood between major depressive episodes. The frequency of SAD seems to vary with geographic location.
How can Seasonal Affective Disorder be treated?
In many ways, the treatment of SAD is similar to that of other major depressive episodes, utilizing antidepressant or mood stabilizing medication and/or psychotherapy. In addition, the exposure to bright light has been found to be an effective means of treating seasonal affective disorder. The individual sits in front of a bright light unit, a specialized, portable box which houses balanced spectrum fluorescent tubes. An individual’s needs for light therapy specifies the duration of exposure and the optimal time of day. An individual should meet periodically with their health care professional and the dose of light therapy can be adjusted as needed.
What causes S.A.D.?
Change in sunlight exposure is the key. The amount of day light exposure one receives and the changes in sunrise/sunset reducing the daylight hours in the fall and winter can affect suffers of S.A.D. The most commonly believed hypothesis follows: although the body has natural daily rhythms, they are not fully precise and rely on the intensity of sunlight to provide adjusting cues. These cues originate in the retina at the back of the eye, creating signals which pass through the optic nerve to the mid brain, setting in motion a number of chemical changes. These changes include:
1) Increase in the neurotransmitter serotonin, necessary for a sense of well being.
2) Regulation and suppression of the hormone melatonin, which is a factor in normal sleep patterns and may influence sleeps recuperative benefits.
Basics of Bright Light Therapy Devices
The most common device used for bright light therapy is a fluorescent light box which produces a light intensity of 2,500 to 10,000 lux at a comfortable distance (1-2′). Light box intensity ratings are always at a given distance. Light weight portable boxes and those mounted on a stand are available. Full-spectrum light is not necessary since intensity is most important, but a balanced-spectrum light minus UV-B emissions is considered ideal. Fewer headaches and eyestrain are associated with using balanced spectrum light. Most light boxes cost from $250 to $525. Light visors which use a battery pack, are worn on the head and allow for mobility. Light visors success rates appear to be somewhat lower. Dawn/dusk simulators are rheostat timers which are used in conjunction with a bedside lamp. These units gradually turn on the lamp light over a preset or variable period of time. Dawn/dusk simulators appear to be most effective for those with mild symptoms, for those who did not succeed with bright light therapy, and for those who have success with bright light therapy but still have difficulty waking up.
How Light Boxes Are Used
The light box is placed in front of the user at the recommended distance for the desired intensity. One should be directly in front of the unit as the light shines into the users eyes. The eyes need be open, and sunglasses should not be worn. Some may be instructed to look at the light box briefly at regular intervals. For many this doesn’t seem to be necessary. The light box intensity of 10,000 lux is much brighter than normal indoor light which is usually 300-500 lux, but not as bright as summer sunlight which can be as bright as 100,000 lux.
Exposure time is determined by the intensity of the light source . There are individual differences, but a 1/2 hour treatment at 10,000 lux or a 1 hour session at 5,000 lux once a day is the average. Most are comfortable with the 10,000 lux intensity level, and choose a unit that produces 10,000 lux at a usable and comfortable 13-16″ distance from the light box. If eyestrain occurs it may be necessary to have shorter periodic sessions.
Persons suspecting that they may have SAD should consult a qualified healthcare provider.
Literature concerning SAD that is distributed by MRC Healthcare, Inc. is offered for information purposes only and should not be considered a substitute for the advice of a healthcare provider.