What is S.A.D.?

Seasonal Affective Disorder (S.A.D.) is a pattern of seasonal depression experienced by otherwise healthy and happy people.  Typically, fall and winter bring “down” feelings not explained by day to day experiences.  It is estimated that as many as 20-30% of the population living at latitudes similar to Seattle's may experience at least some S.A.D. symptoms. The most typical symptoms of S.A.D. are:

Mood changes

• Increased sadness
• Higher irritability
• Greater anxiety

• Increased appetite
• Craving of carbohydrates and sweets

Sleep and activity changes

• Increased sleep duration
• Lower quality of rest
• Daytime tiredness

Menstrual difficulties

Mood lifts with onset of spring or movement toward equator

Because of the seasonal pattern and the fact that S.A.D. occurs more frequently in northern latitudes, it is thought to be caused by the body's reactions to reduced natural light. The mechanism mostly widely thought to be responsible is altered production or uptake of serotonin in the brain. Other possibilities include abnormally delayed circadian rhythms, or abnormal patterns of melatonin secretions. Regardless of the cause, photo (light) therapy has been widely demonstrated to be an effective treatment for S.A.D.

Light therapy requires very bright light. The light box used in the Counseling Center, produces 10,000-lux. This is approximately 20 times brighter than normal room lighting. Since light intensity drops off sharply with distance, it is best to sit near the light - about 23 inches away is optimal. Sit with your eyes open. Exposure to other skin areas will have little or no positive effect. The light box sits at eye level on an angle to provide the most comfortable and effective exposure without excessive glare. Reading at the desk, or just sitting in a chair facing the light about two feet away is all that is necessary.

At this light level, 20-30 minutes a day is an appropriate treatment. Most persons who benefit from light therapy experience positive changes within two days to two weeks of daily treatment. If symptoms do not improve, increasing the treatment up to 45 minutes a day, or using briefer periods twice a day, may be worth trying. Daily, or almost daily, treatment is likely to have the best effect. You may find it helpful to increase the length of exposure during the darkest winter months. Since symptoms may return after cessation of treatment, many S.A.D. sufferers find repeated treatment periods during the fall-winter season most effective. There is some research evidence to suggest that light exposure in early morning may be more effective than afternoon exposure. It is best to avoid exposure to bright lights in the late evening as this may shift the timing of your sleep period.

Though side effects are uncommon and generally mild, light therapy users sometimes complain of irritability, eyestrain, headaches, dry eyes or insomnia. Reducing the period of daily treatment or sitting farther from the light will usually eliminate such effects. The light box shields out most potentially harmful ultra-violet-B light.

Research to date has found no indication that exposure to light therapy devices can harm the retina or in any way cause or accelerate eye disease.

While no such side effects have yet been seen, if you have any history of visual difficulties (apart from the need for ordinary corrective lenses), be sure to consult with your eye doctor before undertaking light therapy.

Most studies have shown that about 75% of S.A.D. sufferers experience improvement when using light therapy. Though results cannot be guaranteed, this is a high success rate compared to treatments available for other forms of depression. You can increase your chances of success by adding some of the following to your self-care plan:

• Take daily walks outdoors
• Set a timer to turn a light on early in your bedroom, or try a dawn simulator for a more gradual artificial dawn
• Increase aerobic exercise, particularly under bright lighting conditions
• Take opportunities to travel south during the winter season
• Take steps to manage your stress
• Consider counseling to help with self-esteem issues and stress management
• Consider counseling or medication to manage other forms of depression

Research on the use of light therapy for conditions other than S.A.D. is in its infancy, but some of the possible applications include the resetting of delayed or advanced sleep phases (extreme “night owls” vs. extreme “early birds”), as well as treatment of premenstrual syndrome, jet lag, and seasonal insomnia. The light box is not a recommended treatment for such concerns at this time.

Feelings of sadness, lethargy, and hopelessness are also symptoms of other forms of depression that do not necessarily lift with a change in seasons.  Counseling and/or medication are still the most effective means of combating non-seasonal depression, but light therapy may be of moderate assistance. For this reason it is always wise to consult with a counselor to determine the most appropriate form of treatment before attempting ‘self-medication’ with light therapy or drugs. 

There are no known negative effects of using light therapy in conjunction with counseling or medication, but some commonly used antidepressants do increase skin sensitivity to light.  If this occurred, one would want to reduce either the length of light exposure or the light intensity used.

Barr, B.C. (2000). Banishing the blues of seasonal affective disorder .

Rosenthal, N.E. (1998). Winter blues.