According to The National Institute of Mental Health;
Seasonal Affective Disorder (SAD) is a type of depression that comes and goes with the seasons, typically starting in the late fall and early winter and going away during the spring and summer. Depressive episodes linked to the summer can occur, but are much less common than winter episodes of SAD.
Risk Factors that may increase your risk of SAD include:
Being female. SAD is diagnosed four times more often in women than men.
Living far from the equator. SAD is more frequent in people who live far north or south of the equator.
Family history. People with a family history of other types of depression are more likely to develop SAD than people who do not have a family history of depression.
Having depression or bipolar disorder. The symptoms of depression may worsen with the seasons if you have one of these conditions (but SAD is diagnosed only if seasonal depressions are the most common).
Younger Age. Younger adults have a higher risk of SAD than older adults. SAD has been reported even in children and teens.
There are four major types of treatment for SAD:
Selective Serotonin Reuptake Inhibitors (SSRIs) are used to treat SAD. The FDA has also approved the use of bupropion, another type of antidepressant, for treating SAD.
Light therapy has been a mainstay of treatment for SAD since the 1980s. The idea behind light therapy is to replace the diminished sunshine of the fall and winter months using daily exposure to bright, artificial light. Symptoms of SAD may be relieved by sitting in front of a light box first thing in the morning, on a daily basis from the early fall until spring. Most typically, light boxes filter out the ultraviolet rays and require 20-60 minutes of exposure to 10,000 lux of cool-white fluorescent light, an amount that is about 20 times greater than ordinary indoor lighting.
Cognitive behavioral therapy (CBT) is type of psychotherapy that is effective for SAD. Traditional cognitive behavioral therapy has been adapted for use with SAD (CBT-SAD). CBT-SAD relies on basic techniques of CBT such as identifying negative thoughts and replacing them with more positive thoughts along with a technique called behavioral activation. Behavioral activation seeks to help the person identify activities that are engaging and pleasurable, whether indoors or outdoors, to improve coping with winter.
At present, vitamin D supplementation by itself is not regarded as an effective SAD treatment. The reason behind its use is that low blood levels of vitamin D were found in people with SAD. The low levels are usually due to insufficient dietary intake or insufficient exposure to sunshine. However, the evidence for its use has been mixed. While some studies suggest vitamin D supplementation may be as effective as light therapy.
