According to the National Institute for Mental Health, approximately 10 percent of Americans currently suffer from Seasonal Affective Disorder (also known as SAD) and related disorders.

SAD is a disorder characterized by drastic mood swings and depression that occur during the winter months; especially in the colder, Northern climates where outdoor activity is diminished and the amount of natural sunlight is lessened by the shorter days.

What are the common symptoms?
SAD sufferers have the following symptoms that occur during the fall/winter months and diminish in the spring:
- Depression
- Increased appetite
- Weight gain
- Inability to concentrate
- Depressed energy and interest
- Excessive sleeping

What to do if you think you have SAD.
If you have any of these symptoms, especially during the winter months or during dark, dreary days, please see your doctor immediately. The truth is SAD is a very treatable ailment.

How is SAD treated?
In 1980, Dr. Alfred Lewry discovered that bright light blocks the release of melatonin and helps relieve seasonal depression. Light therapy, also known as Phototherapy is the most common treatment and usually involves sitting in front of a light box for approximately 30 minutes each day. Consult a physician before starting any light therapy.

Author's Bio: 

Nicole Niemiec is founder of http://www.healthy-insights.com, a site containing reliable health information for improving your quality
of life.