Winter is here! With the abrupt beginning of winter, many people are having mood problems. Research has shown that mood can be affected by the reduced amount of sunlight during the winter months. This pattern occurs winter after winter. Mental health professionals have a name for this winter depression - Seasonal Affective Disorder or SAD.

How common is SAD? Studies in Alaska and Canada show that up to 10 percent of the population has a recurrent winter depression. Two to five percent of the population in the Northern Plains states may have SAD. Women are affected more by seasonal changes in light. The further south, the less common it is. As many as 10 million have it in the USA. Even though there are bright sunny days in northern climates, the angle of the sun is such that the light exposure is not intense enough to affect the neurochemistry of the brain.

What are the symptoms associated with SAD or winter depression? Depression is triggered by reduced light. The symptom pattern for SAD involves extreme fatigue and lack of energy, an increased need for sleep, increased appetite and weight gain. Victims of SAD have normal moods and are more energetic in the summer and spring. In the late fall and winter they feel depressed but are not usually to the point of a major depression. They don't function as well. A typical pattern might be becoming a "couch potato" in the evenings in the winter. The loss of energy and increased fatigue are noticeable. People can barely keep up with the minimal activities they need to do. Only ten percent of people with SAD are ever hospitalized.

How is winter depression different from "Holiday Blues?" Holiday blues have more to do with over commitment, guilt, high expectations and family issues connected with the Holidays. This is more psychological than biological like SAD.

Besides moving to Florida, what can people do about SAD? There is an exciting therapy which helps 60 to 80 percent of the people with SAD. People improve with exposure to bright artificial light. It is called light therapy. By sitting under a bright light for as little as 30 minutes a day they improve. The side effects are mild. Sometimes antidepressant medications help. Recent research suggests that light therapy needs to be implemented for three weeks to have a full effect.

This isn't any ordinary light. It ranges from 5,000 to 10,000 lux and includes the full spectrum of light from the sun. Ordinary light from fluorescent bulbs does not have full spectrum light. The typical cost of a bright light is $250. Most insurance doesn't cover the cost even though SAD is an authentic disorder. Light therapy has proven itself effective in clinical trials against antidepressant and placebo light treatments. In fact, morning treatment for light therapy has been proven to be twice as effective as evening treatment. The only side effects are eyestrain and mild headaches the first few days.

How does this work exactly? Nobody knows but there are some theories. One is that people with SAD have a biological clock that runs slower in the winter. Exposure to bright light affects hormones in the brain to reset the clock back to normal.

Specifically, the bright light advances the onset of the hormone melatonin from a light-sensitive part of the brain that controls our sleep and awake cycle. It helps SAD patients to have an earlier sleep schedule. Light treatment may also affect imbalances in chemical neurotransmitters in the brain.

What do you do if you think you might have SAD? People need to see their family physician to be evaluated for any physical problem that mimics depression. They then may be referred to a psychiatrist who deals with SAD. Once they have been properly screened and diagnosed they can be treated with a special light therapy device or medication. With help, the problem of SAD will probably be gone and winter can become a wonderful time of the year.

Thanks to Mary Ann Kaul, R.N. for her assistance with this article.