What Does SAD Feel Like?

Brenda is a 37 year old woman who came to her internist in November complaining of extreme fatigue. She had difficulty waking up in the morning and found it increasingly more of an effort to get anything done. She had no energy, little interest in her friends and was irritable. She had gained 6 pounds and seemed drawn to sweets. Her work was not getting done, the house was not picked up and she felt more hopeless and depressed each day. Her history reflected similar problems each winter and she looked forward to spring when she became "her usual high energy self."

What Causes the Symptoms and Who Gets Them?

Brenda was suffering from Seasonal Affective Disorder (SAD), often referred to as winter depression. The disorder is brought on by the lack of bright light during the shortened days of winter. Sometimes called the hibernation response, the incidence of SAD increases with increasing latitude and is most prevalent in northern regions with their prolonged winter nights. An estimated 6% of the population suffers from full blown SAD. Another 14% experience a sub-clinical level of SAD resulting in the common winter doldrums. Women outnumber men 3 to 1 in reporting the disorder. Hormonal connections are being explored as the incidence of SAD increases after puberty and is reported less frequently by older women. It has also been associated with worsened PMS symptoms.

The patient's tendency to overeat, oversleep, crave carbohydrates and experience weight gain are characteristic of SAD. These symptoms are considered atypical in contrast to the reduced sleep, poor appetite and weight loss associated with classic melancholic depression. Diagnosis is made on these "atypical" symptoms and the patient's history of reoccurring winter blues, remitting in the spring.

Although researchers disagree on the exact cause, many theorize that there exists a lack of enough morning light to suppress the hormone melatonin. Studies show that blood levels of melatonin are immediately suppressed by exposure to bright light boxes.

What Kind of Treatment is Available?

Light therapy is the preferred choice of treatment because it is non-invasive and has a high success rate. Researchers recommend an ophthalmological and medication history to screen patients who have retinal problems or are taking photosensitizing agents. Those patients should receive an ophthalmological exam and be monitored closely or excluded from light therapy. Leading medical centers successfully treat sleep and mood disorders with light therapy including our own Oregon Health Science University.

How are patients treated?

Therapeutic response is achieved by replacing the light normally found in a long summer day with artificial light. The patient is placed in front of a light box that emits intense bright light. The light enters the eye, hits the retina and is transmitted by nerve impulses to the pineal gland which controls melatonin secretion. Intense bright light is the key; full spectrum light is not required or recommended.

Intensity:

The brightness of light is measured in Lux. Therapeutic light boxes emit 2,500 to 10,000 Lux, 10 to 40 times brighter than ordinary room light.

Duration:

Treatment duration varies but ranges from 15 minutes to 2 hours daily. The higher intensity light boxes require less time.

Timing:

The timing of treatment may also be critical. Although some researchers argue that any time is effective, most research has indicated that morning light is far more effective.

Exposure Method:

Patients are cautioned not to stare at the light, but to engage in reading or other productive activities while sitting at a prescribed distance from the light. Many read, watch television, do paperwork or eat breakfast.

Response:

Relief begins in 3 to 4 days and is usually complete within 2 weeks. Response if frequently dramatic and patients who have suffered for years are profoundly relieved. Remission of symptoms continues as long as the light sessions are continued. Sessions can be discontinued when spring arrives with its longer day duration.

Light units should be designed to meet researchers specifications and be calibrated so the patient knows at what distance to sit in order to receive the proper Lux level.

Some insurance companies reimburse for the purchase of light boxes. The Diagnostic and Statistical Manual of the American Psychiatric Association lists the disorder as DSMIV-296.3X with "seasonal pattern," and this coding should be used in applying for insurance coverage.

What are the Other Applications of Light Therapy?

Light deprivation -- the primary cause of SAD -- is usually the result of the shorter days and longer nights of winter. But light deprivation may also be due to insufficient light exposure from indoor working conditions, health and age-related indoor confinement, shift work schedules, or unseasonably cloudy weather.

Light therapy is an exciting, fast growing field. It is used to treat phase-advanced/phase-delayed sleep disorders, PMS, and age-related insomnia. In can be instrumental in helping people overcome jet lag and shift work schedule adjustments.