Seasonal Affective Disorder, or SAD, is a type of recurrent major depressive disorder in which episodes of depression occur during the same season each year. This condition is sometimes called the "winter blues."
Seasonal affective disorder (also called SAD) is form of depression in which people experience depressive episodes during specific times of the year. The most common seasonal pattern is for depressive episodes to being in the fall or winter and diminish in the spring. A less common type of SAD, known as summer depression, usually begins in the late spring or early summer. SAD may be related to changes in the amount of daylight a person receives.
SAD is not considered as a separate disorder, but rather is a type of depression that has a recurring seasonal pattern. To be diagnosed with SAD, an individual must meet criteria for major depression coinciding with specific seasons for at least two years. The individual must experience seasonal depressions much more frequently than any non-seasonal depressions.
Seasonal affective disorder is estimated to affect 10 million Americans. Another 10 percent to 20 percent may have mild SAD. SAD is four times more common in women than in men. The age of onset is estimated to be between the age of 18 and 30. Some people experience symptoms severe enough to affect quality of life, and 6 percent require hospitalization. Many people with SAD report at least one close relative with a psychiatric disorder, most frequently a severe depressive disorder (55 percent) or alcohol abuse (34 percent).
Not everyone with SAD has the same symptoms, but symptoms commonly associated with the "winter blues" include the following:
Symptoms of summer SAD are:
Either type of SAD may also include some of the symptoms that are present in major depression, such as feelings of guilt, a loss of interest or pleasure in activities previously enjoyed, ongoing feelings of hopelessness or helplessness, or physical problems such as headaches and stomach aches.
Symptoms of SAD tend to reoccur at about the same time every year. To be diagnosed with SAD, the changes in mood should not be a direct result of obvious seasonal stressors (like being regularly unemployed during the winter). Usually, this form of depression is mild or moderate. However, some people experience severe symptoms that leave them unable to function in their daily lives.
Seasonal affective disorder can be misdiagnosed as hypothyroidyism, hypoglycemia, or a viral infection such as mononucleosis.
The cause for SAD is unknown. One theory is that it is related to the amount of melatonin in the body, a hormone secreted by the pineal gland. Darkness increases the body's production of melatonin, which regulates sleep. As the winter days get shorter and darker, melatonin production in the body increases and people tend to feel sleepier and more lethargic.
Another theory is that people with SAD may have trouble regulating their levels of serotonin, which is a major neurotransmitter involved in mood. Finally, research has suggested that people with SAD also may produce less Vitamin D, which is believed to play a role in serotonin activity. Vitamin D insufficiency may be associated with clinically significant depression symptoms.
There are several known risk factors that increase an individuals chance of developing SAD. For example, SAD is more frequent in people who live far north or south of the equator. Additionally, people with a family history of other types of depression are more likely to develop SAD than people who do not have this family history.
Treatment approaches to alleviate the symptoms of SAD typically include combinations of antidepressant medication, light therapy, Vitamin D, and counseling.
Because winter depression may be caused by a reaction to a lack of sunlight, broad-band light therapy is frequently used as a treatment option. This therapy requires a light box or a light visor worn on the head like a cap. The individual either sits in front of the light box or wears light visor for a certain length of time each day. Generally, light therapy takes between 30 and 60 minutes each day throughout the fall and winter. The amount of time required varies with each individual. When light therapy is sufficient to reduce symptoms and to increase energy level, the individual continues to use it until enough daylight is available, typically in the springtime. Stopping light therapy too soon can result in a return of symptoms.
When used properly, light therapy seems to have few side effects. The side effects that do arise include eyestrain, headache, fatigue, irritability, and inability to sleep (when light therapy is used too late in the day). People with manic depressive disorders, skin that is sensitive to light, or medical conditions that make their eyes vulnerable to light damage may not be good candidates for light therapy.
When light therapy does not improve symptoms within a few days, then medication and behavioral therapies such as CBT should be introduced. In some cases, light therapy can be used in combination with one or all of these therapies.