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Seasonal Depression (Seasonal Affective Disorder)

Do the winter months get you down more than you think they should? If so, you might have seasonal depression, also known as seasonal affective disorder (SAD).

Seasonal depression is a mood disorder that happens every year at the same time. A rare form of seasonal depression, known as "summer depression," begins in late spring or early summer and ends in fall. In general, though, seasonal affective disorder starts in fall or winter and ends in spring or early summer.

What Causes Seasonal Affective Disorder?

While we don't know the exact causes of SAD, some scientists think that certain hormones made deep in the brain trigger attitude-related changes at certain times of year. Experts believe that SAD may be related to these hormonal changes. One theory is that less sunlight during fall and winter leads to the brain making less serotonin, a chemical linked to brain pathways that regulate mood. Having too little serotonin may contribute to feelings of depression, along with symptoms of fatigue and weight gain.

SAD usually starts in young adulthood and is more common in women than men. Some people with SAD have mild symptoms and feel out of sorts or irritable. Others have worse symptoms that interfere with relationships and work.

Because the lack of enough daylight during wintertime is related to SAD, it's seldom found in countries where there's plenty of sunshine year-round.

What Are the Symptoms of SAD During Winter?

People with SAD have many of the normal warning signs of depression, including:

  • Less energy
  • Trouble concentrating
  • Fatigue
  • Greater appetite
  • Increased desire to be alone
  • Greater need for sleep
  • Weight gain

What Are the Symptoms of SAD During Summer?

  • Less appetite
  • Trouble sleeping
  • Weight loss

How Is SAD Diagnosed?

If you've been feeling depressed and have some of the above symptoms, see your doctor for an assessment. He or she will recommend the right form of treatment for you.

How Is Seasonal Depression Treated?

There are different treatments,  depending on the severity of your symptoms. Also, if you have another type of depression or bipolar disorder, the treatment may be different.

Many doctors recommend that people with SAD get outside early in the morning to get more natural light. If this is impossible because of the dark winter months, antidepressant medications or light therapy (phototherapy) may help.

What Is Light Therapy for SAD?

Light therapy uses a full-spectrum bright light that is shined indirectly into your eyes. When you use this therapy, you sit about 2 feet away from a bright light -- about 20 times brighter than normal room lighting. The therapy starts with one 10- to 15-minute session per day. Then the times increase to 30 to 45 minutes a day, depending on your response. It's important not to look directly at the light source of any light box for extended periods in order to minimize the possible risk of damage to your eyes.

Some people with SAD recover within days of using light therapy. Others take much longer. If the SAD symptoms don't go away, your doctor may increase the light therapy sessions to twice daily. People who respond to light therapy are encouraged to continue it until they can be out in the sunshine again in the springtime.

WebMD Medical Reference

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