Seasonal Affective Disorder, with the apt acronym SAD, is a form of depression that occurs only during a certain time of year. Most often occurring in the winter months, SAD has been linked to the shorter duration of sunlight. It’s believed that fewer daylight hours cause the brain to produce less serotonin. Research indicates that lower levels of serotonin are more likely in persons who suffer from all kinds of depression, but many of the links between brain chemistry and mood are unknown. Some experts also think that melatonin, a hormone key to sleep, may also impact SAD. People typically begin to suffer from SAD in their mid-teens. As you age, your likelihood of being affected by the condition decreases.
Because SAD is linked to a lack of sunlight, light therapy is the most common course of treatment. There are two types of light therapy: bright light treatment or dawn simulation. Bright light treatment requires the patient to sit in front of a “light box” for a period of time each day, usually in the morning. Dawn simulation is used during sleep. It consists of a low-intensity light that is timed to turn on at a certain time in the morning before you awake, and gradually brightens. Most people find dawn simulation more convenient, however studies have show that bright light therapy is more effective.
It may take up to two weeks for light therapy to take effect. The therapy must be continued throughout the winter, or else relapses in depression are likely to occur.
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