Seasonal affective disorder is a type of depression that occurs during the same season each year. Researchers think that SAD is caused by changes in the level of exposure to sunlight. Light therapy is the main treatment for SAD. Medications and psychotherapy (talk therapy) may help reduce symptoms.
Seasonal affective disorder is a type of depression that occurs during the same season each year. It usually happens in the fall or winter, but some people may experience season-linked symptoms in the summer.
Signs & Symptoms
The list of signs and symptoms of SAD is the same as the list for major depression. However, with SAD, these signs and symptoms appear and disappear at about the same time each year.
The major symptom is a sad, despairing mood that:
is present most days and lasts most of the day
lasts for more than two weeks
impairs the person’s performance at work, at school or in social relationships.
Other symptoms of depression include:
changes in appetite and weight
loss of interest in work, hobbies, people or sex
withdrawal from family members and friends
feeling useless, hopeless, excessively guilty, pessimistic or having low self-esteem
agitation or feeling slowed down
trouble concentrating, remembering and making decisions
crying easily or feeling like crying but not being able to
thoughts of suicide (which should always be taken seriously)
a loss of touch with reality, hearing voices (hallucinations) or having strange ideas (delusions).
Causes & Risk Factors
SAD appears to be triggered by changes in the amount of sunlight. Researchers have several theories about how this happens. Changes in light may:
upset a person's biological clock, which controls sleep-wake patterns
Women are more likely than men to be diagnosed with SAD.
SAD is more common in people who live either far north or far south of the equator.
Young people are more likely to develop SAD. The risk decreases with age.
A family history of SAD or other forms of depression increases risk.
Diagnosis & Treatment
Many people who have SAD are helped by exposure to bright artificial light (light therapy). Various types of light devices are available and can be used at home.
Side-effects of light therapy are usually mild. They include:
Other treatments for depression including pharmacotherapy (medications); psychoeducation; psychotherapy; and brain intervention therapies, such as electroconvulsive therapy (ECT), repetitive transcranial magnetic stimulation (rTMS) and magnetic seizure therapy (MST), are also effective for people with SAD. These treatments may be used individually or in combination.
Increasing exercise and spending more time outdoors may also help to reduce symptoms.