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Seasonal Affective Disorder

Seasonal affective disorder (SAD) is a form of depression that affects about 10 million Americans. People with SAD may have the common symptoms of depression including changes in mood, appetite, energy level and sleeping patterns. In SAD, however, the symptoms follow the seasons of the year. The depressive symptoms of SAD usually:

  1. begin in the fall
  2. peak in the winter
  3. clear up in the spring and summer

SAD is sometimes referred to as winter depression.  Yet, a small minority of patients will experience these symptoms in the summer months.  This is called summer depression.


Patients with SAD usually experience symptoms at about the same time each year. People with the more common form of SAD usually exhibit these symptoms with the change from fall to winter:

  • have less energy in the colder months
  • crave carbohydrates and sweets
  • gain weight
  • sleep a great deal

Individuals with summer depression more often have the more severe symptoms of:

  • poor appetite
  • weight loss
  • insomnia

Other depressive symptoms with both forms of SAD may include:

  • difficulty concentrating
  • irritability
  • crying episodes
  • in extreme cases, thoughts of suicide

Risk Factors for SAD

  • Location – People who live in northern parts of the world or in locations with a reduced amount of daylight or sun are more likely to experience SAD.
  • Gender – The disorder is at least 4 times as common in women as in men.
  • Age – SAD is most likely to occur in people in their 30s.
  • Heredity – Many experts believe that this disorder may be inherited, but this is not certain.


Light Therapy

Because SAD is caused by a lack of sunlight, your doctor may instruct you to use a light box or a light visor that you wear on your head like a cap. These devices are usually used for about 30 minutes each day throughout the fall and winter months, or as directed by your doctor. Your doctor will instruct you on the proper distance to sit from the light. You are able to eat and read under the light.

While you are using the light box or visor, your eyes should remain open, but you should not look directly into the light source. Results from light therapy vary, and you may need several weeks of daily treatment before your symptoms improve. Usually, light therapy is continued until the spring.

Side Effects

Light therapy does not have any serious side effects. Some patients, however, may experience:

  • insomnia
  • headaches
  • eyestrain
  • irritability

Insomnia may occur if therapy is performed too late in the day. For this reason, most experts recommend using light therapy in the morning. Ultraviolet sources of light therapy, such as tanning beds, are not recommended for SAD. It is not advisable to use a light box that is homemade.


Antidepressant drugs are also used to treat SAD. The ones used most often are called selective serotonin reuptake inhibitors (SSRIs). The doses used to treat SAD are similar to the doses used to treat depression. These include:

  • Prozac
  • Zoloft
  • Paxil
  • Celexa

You should discuss any specific questions concerning these medications with your doctor or pharmacist. You should be sure to mention any prescription and over-the-counter drugs or nutritional supplements you are taking, because these medications may interact with SSRIs.

Side Effects

The side effects of SSRIs include

  • changes in sex drive or performance
  • nausea
  • diarrhea
  • insomnia

Other Treatments

In addition to light therapy, your doctor may recommend:

  • exercise – you should get plenty of exercise during the months you are affected by SAD

If your symptoms are severe, your doctor may also recommend: 

  • psychotherapy
  • counseling

Your doctor will determine whether light therapy, antidepressant therapy, behavioral therapy, or a combination of treatments is best for you.


Fortunately, SAD is very treatable, and there are many excellent resources available to help you better understand this condition. Some of these resources are:

For more information:

Go to the Anxiety and Stress Disorders health topic.