Seasonal Affective Disorder (SAD) is a debilitating, mood disorder with a predictable pattern of recurrence during the fall and winter. Experts estimate that as many as 10 million North Americans may experience SAD. Initial symptoms may include feelings of lethargy, trouble waking and getting up or cravings for heavy or carbohydrate-rich foods.
These initial symptoms often lead to a mild mood disorder for a few weeks and then may progress to chronic low mood, inability to do work, loss of pleasure in usual activities, etc. Symptoms are often most acute in January and February. The severity of symptoms, are the indicator experts use to differentiate mild winter blues from more acute SAD. With both conditions, as days become longer, symptoms tend to clear up usually by early May.
Anyone can experience SAD cycles, even thought they may not occur every year. Women of childbearing age appear to be the most vulnerable, but SAD may occur from childhood through to old age, and men can be just as strongly affected as women.
Bright light therapy is simple to administer and effective for many SAD sufferers when using a well-designed bright light therapy system on a regular daily schedule. Bright light may be "dosed" by changing the intensity level, exposure duration and/or the time of day when it is used. Generally, the recommended starting dose is 10,000 LUX for 30 minutes in the morning soon after waking. Dosage is then adjusted (increased or decreased) to suit the specific needs of the user.
One large study of SAD patients undergoing bright light therapy, published in the Archives of General Psychiatry, found significant clinical improvement in about 80% of cases when bright light was scheduled at the optimum early hour. If the bright light was scheduled later, the response rate dropped to about 40%.
To determine the optimum treatment time for bright light therapy, the Automated Morningness-Eveningness Questionnaire provided by CET (Center for Environmental Therapeutics), is an excellent guide. It may be used in consultation with your physician to prepare an appropriate bright light therapy treatment schedule for your individual condition.
