Seasonal Affective Disorder (SAD)

What is seasonal affective disorder (SAD)?

Seasonal affective disorder, or SAD, is a type of depression that affects a person during the same season each year. If you get depressed in the winter but feel much better in spring and summer, you may have SAD.

Anyone can get SAD, but it is more common in:

What causes SAD?

Experts are not sure what causes SAD, but they think it may be caused by a lack of sunlight. Lack of light may upset your sleep-wake cycle and other circadian rhythms, and it may cause problems with a brain chemical called serotonin that affects mood.


Symptoms come and go at about the same time each year. For most people with SAD, symptoms start in September or October and end in April or May.

How is SAD diagnosed?

It can sometimes be hard to tell the difference between non-seasonal depression and SAD, because many of the symptoms are the same. To diagnose SAD, your doctor will want to know if:

How is it treated?

Doctors often prescribe light therapy to treat SAD. There are two types of light therapy:

Light therapy works well for most people with SAD, and it is easy to use. You may start to feel better within a week or so after you start light therapy. But you need to stick with it and use it every day until the season changes. If you don't, your depression could come back.

Other treatments that may help include:

If you think you may have SAD contact your physician for an appointment.

Please enter the word you see in the image below: