Seasonal Affective Disorder

What is seasonal affective disorder?

Seasonal affective disorder (also called SAD) is a type of depression that follows the seasons. The most common type of SAD is called winter depression. It usually begins in late fall or early winter and goes away by summer. A less common type of SAD, known as summer depression, usually begins in the late spring or early summer. It goes away by winter. SAD may be related to changes in the amount of daylight during different times of the year.

How common is SAD?

As many as 6 of every 100 people in the United States may have winter depression. Another 10% to 20% may experience mild SAD. SAD is more common in women than in men. Although some children and teenagers get SAD, it usually doesn't start in people younger than 20 years of age. For adults, the risk of SAD decreases as they get older. SAD is more common in northern geographic regions.

How does my doctor know I have SAD?

Although your symptoms are clues to the diagnosis, not everyone with SAD has the same symptoms. Common symptoms of winter depression include the following:

• A change in appetite, especially a craving for sweet or starchy foods
  
• Weight gain
  
• A heavy feeling in the arms or legs
  
• A drop in energy level
  
• Fatigue
  
• A tendency to oversleep
  
• Difficulty concentrating
  
• Irritability
  
• Increased sensitivity to social rejection
  
• Avoidance of social situations
  

Symptoms of summer depression include poor appetite, weight loss and insomnia. Either type of SAD may also include some of the symptoms that are present in other forms of depression. These symptoms include feelings of guilt, a loss of interest or pleasure in activities you used to enjoy, ongoing feelings of hopelessness, and physical problems, such as headaches.

Symptoms of SAD keep coming back year after year, and they tend to come and go at about the same time every year. The changes in mood are not necessarily related to obvious things that would make a certain season stressful (like regularly being unemployed during the winter).

Is there a treatment for SAD?

Yes. Winter depression is probably caused by your body's reaction to a lack of sunlight. Light therapy is one option for treating winter depression.

If your doctor suggests you try light therapy, you may use a specially made light box, or a light visor that you wear on your head like a cap. You will sit in front of the light box or wear the light visor for a certain length of time each day. Generally, light therapy takes about 30 minutes each day throughout the fall and winter, when you're most likely to be depressed. If light therapy helps you, you'll continue using it until enough sunlight is available, typically in the springtime. Stopping light therapy too soon can allow the symptoms to come back.