Bright Light Treatment of Winter Depression
What is Winter Depression?
Winter depression or seasonal affective disorder (SAD) is a syndrome characterized by recurrent depressive episodes which occur during the winter. The onset may begin as early as September or October and the symptoms spontaneously remit in April or May. Individuals suffering from winter depression typically do not experience depressive symptoms during the summer.
Recent studies indicate that more than 10 million Americans suffer from winter depression and many more experience "winter doldrums," a lesser form of winter depression. On average, women are three times more likely than men to suffer from winter depression.
Symptoms of Winter Depression
Decrease physical activity
Difficulty in awakening
What Causes Winter Depression?
Many of the functions of the human body follow a daily (circadian) rhythm which is close to 24 hours in duration. Circadian rhythms are regulated by the body's internal clock and by exposure to sunlight, which synchronizes the body's clock to the 24-hour day.
We believe that winter depression occurs because of a decrease in the amount of light that persons receive during the winter months. Winter days are considerably shorter and frequent cloud cover reduces exposure to sunlight. Reduced sunlight and/or shorter days may result in some of the body's circadian rhythms becoming out of synch with each other, which may trigger the depression.
Treatment with Bright Light
Currently, bright light therapy is the treatment of choice for winter depression. Numerous studies have demonstrated that bright light therapy is safe and effective. However, there still is some disagreement as to how light therapy works and more research needs to be done to understand and improve this form of treatment.
If you would like to be treated with bright light, we strongly recommend that you consult your doctor and be supervised by your doctor during treatment. People respond differently to bright light exposure; it is important that bright light therapy be timed correctly so that you will benefit from this treatment. Also, some medications can make you more sensitive to light. Individuals with retinal problems should have an ophthalmological exam before beginning light therapy.
What Type of Light Works?
We recommend using a light fixture which is able to produce diffuse light of at least 2500 lux at about 3 feet away from the source. Higher intensity lights (10,000 lux) are also available, which reduce the amount of exposure time needed.
Our studies are showing minimal differences between full spectrum and ordinary "cool white" fluorescent lamps. Therefore, we are currently recommending "cool white" fluorescent lamps because they contain less ultraviolet radiation, which some physicians recommend avoiding.