Seasonal Affective Disorder

SAD, or Seasonal Affective Disorder, is a type of depression which occurs cyclically in the fall and winter months, and typically improves or resolves during summer months. If you have seasonal affective disorder, winter's short days and long nights may induce feelings of depression, lethargy, fatigue, cravings for sweets and starches, sleep problems and irritability. If your symptoms of depression are severe, or if you have any thoughts of harming yourself or others, please call CHWS at 253.879.1555 for an appointment with a counselor or medical practitioner, or call 911.

Circadian Abnormalities

Winter depressives show an abnormal relationship between their 24-hour circadian rhythms (body clocks) and sleep. Research has shown a later onset of the morning wakefulness phase of this rhythm in those with seasonal affective disorder compared to non-depressed controls.  Bright light, the best-documented synchronizer of circadian rhythms, acts by shifting the circadian rhythms to a more normal cycle.

Bright Light Therapy

The use of bright light (10,000 lux) used for 30 minutes in the morning has been shown to be effective in normalizing the mood of SAD patients. This light intensity is similar to that of a cloudy day and about 5 to 20 times greater than the brightness of a bright, well-lit office.

A full-spectrum light source is not necessary for the therapeutic effect of bright light therapy; standard cool-white fluorescent tubes are sufficient. Patients are asked to have the light source in their peripheral vision so that they may read or watch TV while having the light treatment. At least one study indicates that the light therapy works via the eyes rather than the skin.

Usually it takes three or four days for a patient to notice a significant response. The response is usually substantial within one to two weeks. The maximal response from a given "dose" of light may not be optimal for four weeks. When light treatment is stopped, relapse may begin within three to four days. After patients have responded to the bright light, some are able to maintain a therapeutic effect with a shorter duration of bright light exposure.

If there is no response after the first two weeks, then the duration, intensity or timing of the light could be altered.

Occasionally patients experience headache, insomnia, or eyestrain. These instances have been resolved with discontinuation or lowering the intensity or duration of the therapy. Persons with diseases of the eyes or those taking photosensitizing medications should check with their physician before using bright light.

Tanning beds should not be used as light therapy. The spectrum of light is inappropriate and damage can occur to the eyes and the skin with the use of tanning beds.

How to obtain SAD light therapy lamps

There are many companies on the internet which sell light therapy lamps. The options are numerous. The ideal exposure should equal 10,000 lux for 30 minutes; however, a lower intensity of light can be substituted by increasing the exposure time.

Some options on the web include:; ; as well as searching for light therapy boxes on (This does not necessarily mean an endorsement of any one resource over another.)