Seasonal Affective Disorder (SAD), formerly called Seasonal Depression, affects between 10 million and 25 million Americans according to Dr. Norman Rosenthal, National Institute of Mental Health. The likelihood that one will suffer from SAD increases the further one goes North, women are four times more likely to experience SAD than men and the age group 20 to 40 is most vulnerable.

SAD is still undergoing a great deal of research. The exact cause is not known nor are its treatments well defined. Researchers, such as Dr. Rosenthal, are studying the link between lack of sunlight and the affects on melatonin, seratonin and other hormones as well as the lack of sunlight and its affect on the body's circadian rhythms.

Current treatments are exploring the effect of light therapy and antidepressants on SAD. However, all treatment plans include exercise. In some cases, exercise may help to prevent or manage SAD. Physiologically, exercise stimulates the brain to release hormones called endorphins, normally credited for suppressing sensations of pain and producing a sense of well-being. Endorphin production usually begins about 15 to 20 minutes into an exercise session and peaks after about 45 minutes. Repetitious movements, such as walking, running and cycling, also increase levels of serotonin.

Researchers at Indiana University found a significant decrease in depression for at least 2 hours after moderate exercise. "You can reap the calming benefits of exercise without running yourself ragged," says Jack Raglin, Ph.D., an associate professor of kinesiology.

The most recommended form of exercise for depression and SAD is simply walking. Most beneficial to those with SAD is walking outdoors.

Marian Brown has been active in holistic health care for over 15 years. She is editor with Holistic Health News. Visit the website http://www.hhnews.com to subscribe for their free email newsletter.