Seasonal Affective Disorder (SAD) - Topic Overview
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:
- People who live in areas where winter days
are very short or there are big changes in the amount of daylight in different
- People between the ages of 15 and 55.
The risk of getting SAD for the first time goes down as you age.
People who have a close relative with SAD.
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
What are the symptoms?
If you have SAD, you
- Feel sad, grumpy, moody, or
- Lose interest in your usual activities.
more and crave
carbohydrates, such as bread and pasta.
- Gain weight.
- Sleep more and feel drowsy during the daytime.
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 nonseasonal depression and SAD, because many of the
symptoms are the same. To diagnose SAD, your doctor will want to know
- You have been depressed during the same
season and have gotten better when the seasons changed for at least 2 years in
- You have symptoms that often occur with SAD, such as being
very hungry (especially craving carbohydrates), gaining weight, and sleeping
more than usual.
- A close relative-a parent, brother, or sister-has
How is it treated?
Doctors often prescribe
light therapy to treat SAD. There are two types of
- Bright light treatment. For this treatment,
you sit in front of a "light box" for half an hour or longer, usually in the
- Dawn simulation. For this treatment, a dim light goes on
in the morning while you sleep, and it gets brighter over time, like a sunrise.
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: