Seasonal Affective Disorder (SAD) and Light Therapy.
Seasonal Affective Disorder (SAD) is a form of depression with symptoms that occur during the winter months and usually subside during the spring and summer months. The main age of onset of SAD is between 18 and 30 years of age. The irregular sleep/wake schedule of most college students may exacerbate SAD because students may sleep very late and spend less time in daylight than most people.
What causes SAD is a topic of ongoing research. What is known is that it has something to do with the amount of sunlight you receive. As seasons change, there is a shift in our “biological internal clocks” or circadian rhythm, due partly to these changes in sunlight patterns. This can cause our biological clocks to be out of “step” with our daily schedules. In addition, Melatonin, a sleep-related hormone secreted by the pineal gland in the brain, has been linked to SAD. This hormone, which may cause symptoms of depression, is produced at increased levels in the dark. Therefore, when the days are shorter and darker the production of this hormone increases.
When used correctly, light therapy can help to alleviate fatigue and lethargy, and provide some relief for depression, during the shorter days of fall, winter, and into spring. Relief from depression may be gotten by spending 30 or more minutes outside in the sun every day because the effect of sun light registering on the brain through the eyes boosts mood. Though this may help many people, the sunlight in winter may not be bright enough to ease symptoms, so artificial light therapy might help depression.
Fall and winter seasons are characterized by a reduced amount of daylight. Research indicates that light affects the receptors in our brain that produce serotonin, which in turn affects people’s mood. Light therapy has been shown to be effective in up to 85 percent of diagnosed cases. A research review commissioned by the American Psychiatric Association in Washington, D.C., concluded that as little as 30 minutes of light therapy 3 or 4 times per week is an effective treatment of seasonal affective disorder (SAD) and other forms of depression. This review appears in the April 2005 American Journal of Psychiatry.
Studies of light therapy for depression have not been limited to SAD (Seasonal Affective Disorder). There is promising evidence that it may be effective in non-seasonal depression as well. Light therapy also works well for bulimia, PMS, Insomnia, and chronic fatigue.
Side effects, although minimal, have been reported by a very few people. These side effects are not dangerous and are usually temporary. They can be remedied by reducing exposure time.
People occasionally report eye irritation and redness that can be alleviated by sitting farther from the lights or for shorter periods. Some people report slight nausea at the beginning of treatment. These usually subside a few hours after treatment is finished and, generally, disappear after several exposures.
The most dramatic side effect, and one that occurs infrequently, is a switch from the lethargic state to an over-active state in which one may have difficulty getting a normal amount of sleep, become restless and irritable (even reckless) and be unable to slow down, or subjectively speedy and “too high”. This state is called hypomania, when milder, and mania when more severe. People who have previously experienced these states in late spring or summer are particularly vulnerable. If this occurs, the use of lights should be reduced or terminated.
It is possible that you may become depressed during a cold or viral infection. Light therapy could at this time cause irritation. However, soon after the infection or virus has cleared up, the positive effects of the light will return.
If you have an eye or skin condition which is affected by bright light you should consult a doctor before embarking on light therapy. Do not undergo the bright light treatment if you are suffering from disorders such as:
Those who have received partial benefit from antidepressants often begin light therapy without changing drug dose. Some people find a combination of light and drug treatment to be most effective.
However, some antidepressant drugs, the tricyclics (imipramine, nortriptyline, desipramine, amitriptyline), as well as lithium, St. John’s Wort, and melatonin, are known or suspected to be “photosensitizers”, i.e., they may interact with the effect of light in the retina of the eyes. Users of antidepressant or other drugs should therefore check with their physician or ophthalmologist (eye specialist) before commencing light treatment.
Please sign our release form before using the light. Thank you.
There are many commercial products for light treatment. Older devices use flourescent lights, newer ones use LED’s and are less expensive. If you attempt to build your own using flourescent bulbs, make sure that you use an plastic diffuser in front of it that will filter out the dangerous UV light that could damage your eyes. Your eyes should receive 10,000 lux for optimal treatment. Lower light levels require longer exposure periods. There is some newere research that suggests you can use much lower intensities of specific frequencies of blue light.
Remember the intensity of the light depends on how close it is to your eyes. If the treatment device delivers 10,000 lux at 12 inches, it will only deliver 2,500 at 24 inches. In other words, to receive the equivalent light you would in 30 minutes at 12 inches you would need 2 hours at 24 inches. (Intensity is proportionate to the inverse of the distance-squared.) If a device claims to deliver 10,000 lux – find out at what distance. Better light boxes will deliver 10,000 lux at 18 inches or more. Cheaper devices require the device to be much closer, which may require some tricky placement.
More recently, research has indicated that it is a certain part of the blue light spectrum that is necessary to reset our circadian rhythms. The blue light does not need to be quite as bright and can be equally effective. Blue LED modules may be excellent choices since they do not create the dangerous ultraviolet light, use less power, and may be more comfortable.
Examples of SAD treatment device are given below. These are not meant as endorsements, just examples of what you can find.
For more information, search “Seasonal Affective Disorder” (SAD) and/or “Light Therapy” at the Mayo Clinic website.