Light Therapy for Seasonal Depression (SAD)
Richard E. Ruhrold, Ph.D., HSPP
Licensed Psychologist
Vice President for Clinical Services
Twenty years of peer reviewed research confirms that light therapy can be a beneficial treatment for depression that has a seasonal pattern of recurrence and remission.
What is “Seasonal Affective Disorder? SAD is a recurrent depressive illness occurring at the same time each year. The most common observed pattern involves onset or worsening of depressive symptoms in autumn with complete or partial remission in spring. Diagnosis of SAD should only be made if a clinically significant depressive illness has occurred at the same time of year on at least three occasions. Symptoms are similar to non-seasonal depressive illnesses though atypical symptoms often include increased sleep, appetite and weight, carbohydrate craving and fatigue with an afternoon slump in energy. These symptoms are particularly common in winter SAD.
Each depressive episode typically starts within the same ninety (90) day period each year and ends during a second ninety (90) day period. Patients with SAD have an increased risk of depressive symptoms at other times of the year as well. In sub-clinical SAD, some people experience changes in energy, sleep and appetite without serious depressed mood during the winter.
What causes SAD? The pineal gland, through its secretion of melatonin, is responsible for maintaining circadian rhythm (the body's biological clock), regulating the endocrine (hormonal) system, and maintaining the integrity of the immune system. The level of secretion of melatonin by the pineal gland is heavily influenced by sunlight. At night, if the amount normally secreted varies significantly, one or more of the following symptoms can occur: disruptions in the sleep/wake cycle, headache, mental and physical fatigue, and irritability. Called `jet-lag' when it occurs after crossing more than two time zones in a plane, this syndrome can also be caused by working rotating shifts and by experiencing other disruptions to a normal sleep/wake cycle. Some people with "seasonal affective disorder" (SAD) experience this syndrome when the low sunlight levels at certain times of the year (winter in northern areas) are not sufficient for their pineal glands to decrease melatonin production to normal low daytime levels.
In its most marked form, SAD affects an estimated 6 percent of the U.S. population (about ten million people). Another 14 percent of the adult U.S. population is estimated to suffer from a lesser form of SAD, known as the winter blues. Though these people are not usually affected severely enough to seek medical attention, they nevertheless feel less cheerful, energetic, creative, and productive during the dark winter days than at other times of the year.
What is “light therapy” or “phototherapy?” Light therapy is the use of daily exposure to high intensity, broad spectrum light to treat the winter form of SAD.
What kind of light should be used for effective light therapy? The light therapy device should be acquired from a reputable vendor (see Appendix). The minimum light intensity to produce a beneficial effect is 2,500 lux. An even brighter light is preferred. In purchasing a light therapy device, consumers should look for a unit that is rated at 10,000 lux brightness at twelve (12) inches from the light source.
The device should have an ultraviolet (UVA/UVB) filter to limit risks associated with exposure to ultraviolet light. (Consumers are discouraged from the use of tanning beds as an alternative “therapy.” Exposure to ultraviolet light from tanning beds and other sources constitutes a serious risk factor for damage to the eyes and skin, the latter being closely associated with the occurrence of various forms of skin cancer. Tanning beds are not used with sufficient frequency to produce a reliable therapeutic benefit. No body of peer-reviewed research exists to support the use of tanning beds to reduce symptoms of SAD. )
How much does a good light therapy device cost? A quality device meeting the specifications discussed above can be obtained for $150 to $250. Some insurance plan may cover part or all of the cost if the consumer has a doctor’s “prescription.” The price may seem high but it is far less than the cost of depression in lost productivity and impaired joy in living.
How long should the light be used? The length of light therapy sessions is dependent on the intensity of the light source. For example, a 2,500 lux light box needs to be used at a minimum of two (2) hours per day, often longer. With a preferred 10,000 lux light box, an hour a day of exposure is usually sufficient, though some individuals need longer exposure, even to the higher intensity light.
What is the best time of day to do light therapy? Most research indicates that light therapy given shortly after waking is typically most effective. Although, if this is impractical, use of the light later in the morning or even splitting the time between early morning and later in the day may be beneficial. Avoid light therapy near bedtime. If treatment is done late in the day, some people may experience insomnia.
How should the light be directed? Light therapy appears to be most effective when exposure is to the eyes. Thus, a frontal placement of the light therapy device is preferred.
When in the year should light therapy be used? Light therapy should begin several weeks prior to the typical time of onset of SAD symptoms and continue during the period in which the individual typically has experienced symptoms.
Does light therapy have any known side effects, cautions or contraindications? The expert consensus literature includes no absolute contraindications for the use of light therapy. Light therapy has been shown to produce relatively limited to mild side effects. The most common side effects are headache, eye strain, nausea, or agitation. Some reports exist of hypomania or mania as the result of light therapy. Consequently, persons who have conspicuous mood swings or have been formally diagnosed with “Cyclothymia” or “Bipolar Mood Disorder” (manic depression) should be monitored closely during light therapy.
While no evidence exists that light therapy is associated with damage to the eyes or retina, patients with ocular risk factors (for example, retinal disease, diabetes, macular degeneration, light-sensitizing medications, such as Lithium, St. John’s Wort, and Phenothiazine anti-psychotics) should have a baseline opthalmological consultation prior to starting light therapy and should undergo periodic monitoring. (Michalak, Lam & Levitt (June, 2002). Current Treatment Recommendations for Seasonal Affective Disorder, Canadian Psychological Association Bulletin, pp. 47-50).
How should I care for a light therapy device? Light therapy devices are not complicated “medical equipment.” They can be kept in good working order through periodic inspection by the consumer and by following the manufacturer’s recommendations for care of the unit.
Can light therapy be used alone or should it be part of a “combination therapy”? In cases of severe and disabling depression and certainly if the individual has experienced any suicidal thinking or behavior, light therapy will probably not be sufficient if used alone. In such circumstances, light therapy should be considered an adjunct to medication and psychotherapy.
Appendix:
Vendors for Light Therapy Devices
Alaska Northern Lights
P. O. Box 1801
Homer, Alaska, 99603
Phone: 1-800-880-6953.
Fax: 907-235-7665
Web Site: www.alaskanorthernlights.com
Apollo Health
376 South Commerce Loop
Orem, Utah, 84057
Phone: 1-800-545-9667
Fax: 801-226-0414
Web Site: www.apollohealth.com
Northern Light Technologies
8971 Henri-Burassa West
Montreal, Quebec H4S 1P7 Canada
Phone: 1-800-263-0066
Fax: 514-335-7764
Web Site: www.northernlighttechnologies.com
Science of Light, Inc.
28 Parker Way
Santa Barbara, California 93101
Phone: 1-800-234-3724
Fax: 805-564-2147
Web Site: www.scienceoflight.com
The Sunbox Company
19217 Orbit Drive
Gaithersburg, Maryland 20879-4149
Phone: 1-800-548-3968
International: 1-301-869-5980
Fax: 301-977-2281
Web Site: www.sunbox.com