If you have episodes of depression that occur only in the fall, winter and early spring, you may have Seasonal Affective Disorder (SAD). The hallmarks of SAD are excessive sleeping, carbohydrate and sugar cravings, lethargy, difficulty concentrating and depression. Although many of the symptoms are similar to non-seasonal depression, if your symptoms go away with the return of longer days, you probably have SAD, and your doctor is likely to recommend light therapy before any other treatment.
Note: Although light therapy may sound like the ultimate do-it-yourself depression treatment, before doing anything, you should get a formal diagnosis of SAD from a doctor, and preferably have them guide your treatment.
Why Light Therapy?
It may be hard to believe that a dose of light every day could treat a mood disorder, but in the case of Seasonal Affective Disorder, it's far and away the most successful treatment. Light therapy replaces the light we are lacking during the winter months of cloudy skies and short days. Not only is light therapy used to treat SAD, but it is also used to adjust sleep cycles (circadian rhythm).
Light from a light box mimics sunlight. Optimally, bright morning light causes the body to suppress the production of melatonin, a sleep regulating hormone. At sunset, the body starts to produce melatonin to help us sleep. For this reason, light therapy, is often used to help regulate sleep cycle - for instance, to prevent jet lag.
In addition, studies have shown that serotonin production is boosted by exposure to sunlight. Low levels of serotonin are associated with depression.
Different forms of light therapy
- Light box
- Head mounted light visor
- Dawn simulators
Light therapy from a light box or visor consists of light entering the patient's retina from a prescribed distance for a prescribed amount of time. Treatment does not and should not require the patient to look directly into the light.
The therapeutic dose for light therapy ranges between 2,500 and 10,000 lux. The bottom of the range is several time the amount you will generally find in a home or office, while 10,000 lux is about the amount of light outside at sunrise on a clear day.
Dawn simulators are not in themselves an effective form of light therapy, but can be utilized either along with light therapy or on their own to make waking up on dark winter mornings easier. At a prescribed time, usually about thirty minutes before the desired wake time, the dawn simulator begins to emit a soft light that grows brighter.
Side effects of light therapy
Possible side effects from light therapy are:
- Dry mouth or eyes
- Mania, euphoria, agitation or hyperactivity similar to bipolar disorder
- Sleep problems
Side effects are generally mild and might go away on their own. If not, they can usually be mitigated by sitting further away from the light source or decreasing the exposure time. Also, dry mouth or eyes can be relieved by using over the counter treatments such as artificial saliva or eye drops.