Seasonal affective disorder, or SAD, often dubbed the "winter blues," afflicts about 10% to 20% of Americans, especially those living in Northern climes, according to the American Psychiatric Association. SAD is a physical condition that can lead to a psychological disorder. As the daylight hours shorten each day, the reduced exposure to light causes a biochemical imbalance in some people's brains. Most people's body clocks, or circadian rhythms, adjust to seasonal changes in light. But those who don't adapt are more prone to winter depression. People with mild to moderate SAD may notice symptoms of depression crop up in early fall. Others say in deep winter they tumble into an emotional pit.
There are a number of effective treatments. The most well established is light therapy, in which patients sit under a special lamp called a light box or don a visor outfitted with a bulb for a prescribed period of time.
Bonnie - light therapy is a good therapy. However, I believe that waning vitamin D stores as the weather cools is also a huge factor in SAD. Test your blood vitamin D levels to see if you are deficient. If needed, supplement with extra vitamin D, in which Cod Liver Oil is the most bioavailable source.
Thanks to the Energy Policy Act of 2005, a longer stretch of lighter mornings in the fall and lighter evenings in the spring should help SAD sufferers.