Seasonal affective disorder (SAD) is a form of depression that occurs during specific seasons, most commonly during the fall and winter. However, the condition can occur at any time of the year, including during the summer. People who get the mood disorder have normal mental health throughout most of the year and experience depressive symptoms around the same time repeatedly, year after year.
The incidence of the condition varies with geography. For example, it tends to be more common in the northern or polar regions.
The cause of SAD is not yet known, but it's believed to be related to the availability of sunlight. Light affects your internal body clock, which helps you regulate when to sleep and when to be awake. Some scientists believe that a fluctuation in the body's production of melatonin, a hormone that helps induce sleep, might be the cause of SAD. Other researchers speculate that a lack of serotonin, a brain chemical or neurotransmitter that seems to be triggered by sunlight, is the cause of SAD. People who are depressed often have decreased levels of serotonin in their brains.
Common symptoms of SAD include:
If you are diagnosed with seasonal affective disorder (SAD), your doctor may choose one of several approaches to your treatment.
Light Therapy — Short periods of exposure to light can help ease depression. Doses of sunlight are measured in "lux." For example, the sun emits about 90,000 lux and blue sky reflects about 45,000 lux. Treatments could range from two hours of light at 2500 lux every morning to 30 to 40 minutes of light at 10,000 lux every morning. However, light therapy in the evening may interrupt sleep patterns.
There are few, if any, side effects to the eyes from using light therapy. Sometimes, an hour walk in the morning can help without any other treatment.
Medication — Your doctor may prescribe an antidepressant in combination with light therapy or if light therapy isn't effective. Antidepressants often are used when the condition occurs in the summer.
Psychotherapy — Psychotherapy may help you identify ways to avoid behaviors or environments that tend to trigger episodes of SAD, or to reduce stress in your life, which may worsen the symptoms.
Carefully timed supplementation of the hormone melatonin.
In addition to the treatments described above, there are a number of things you can do to help your body cope with seasonal depression. For example, try increasing the amount of light in your home or workplace by opening window shades. Increase your physical activity as exercising regularly can help relieve stress. Also, you may want to consider visiting a warm, sunny place during the winter, such as vacationing in a tropical location.