Conditions Basics

What is seasonal affective disorder (SAD)?

Seasonal affective disorder, or SAD, is a type of depression that occurs during the same season each year. It is sometimes called winter depression or seasonal depression.

Anyone can get seasonal affective disorder (SAD), but it's more common in:

• Women.
• People who live far from the equator, where winter daylight hours are very short.
• 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 it?

Experts aren't sure what causes SAD. But they think it may be caused by a lack of sunlight. Lack of light may upset your "biological clock," which controls your sleep-wake pattern and other circadian rhythms. Lack of light may also cause problems with serotonin, a brain chemical that affects mood.

What are the symptoms?

Seasonal affective disorder (SAD) can come and go at about the same time each year. Most people with SAD start to have symptoms in September or October and feel better by April or May.

If you have SAD, you may:

• Feel sad, grumpy, moody, or anxious.
• Lose interest in your usual activities.
• Eat more and crave carbohydrates, such as bread and pasta.
• Gain weight.
• Sleep more but still feel tired.
• Have trouble concentrating.

How is it diagnosed?

To diagnose SAD, your doctor will ask if:

• You have been depressed during the same season and have gotten better when the seasons changed for at least 2 years in a row.
• 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 had SAD.

You may need to have blood tests. The tests can rule out other conditions that can cause similar symptoms, such as low thyroid (hypothyroidism).

Your doctor may also do a mental health assessment to get a better idea of how you feel and how well you are able to think, reason, and remember. It can sometimes be hard to tell the difference between SAD and other types of depression. Many of the symptoms are the same.

How is SAD treated?

Light therapy is the main treatment for SAD. Medicines and counselling may also help.

Light therapy

Light therapy is exposure to light that is brighter than indoor light but not as bright as direct sunlight. The most common light therapy uses a special type of light, called a light box. Experts think it works by resetting your biological clock. It helps most people who have SAD, and it's easy to use.

Antidepressants

Antidepressant medicines may help people who have SAD. They may be used alone or with light therapy. The most common ones prescribed for SAD include:

• Selective serotonin reuptake inhibitors (SSRIs), such as paroxetine (Paxil) and sertraline (Zoloft). SSRIs are usually tried first.
• Other antidepressants, such as bupropion (Wellbutrin) and venlafaxine (Effexor).

If your doctor prescribes an antidepressant, be sure you take it the way you're told to. Do not stop taking it suddenly. This could cause side effects or make your depression worse. When you are ready to stop, your doctor can help you slowly reduce the dose to prevent problems.

Counselling

Counselling may also help. For example, cognitive-behavioural therapy can help you learn more about SAD, how to manage your symptoms, and how to help prevent future episodes.

Caring for yourself

There are things you can do for yourself when you have seasonal affective disorder (SAD).

Regular exercise and getting more sunlight can help. So try to exercise outdoors when the sun is shining. Being active during the daytime, especially early in the day, may help you have more energy and feel less depressed. But any activities that raise your heart rate—including daily chores—can help, especially if you can do them outdoors or near a sunny window.

Some people try complementary treatments to help with SAD. One example is melatonin. It's a hormone that may help regulate your biological clock. If you want to use melatonin or other complementary treatments, be sure to check with your doctor first. These medicines may interact with other treatments.