- The amount of research on light therapy for the treatment of depression is small when compared to the large amount of information on the use of prescription medication and psychotherapy for the same problem. Therefore, conclusions about light therapy are more uncertain.
- Light therapy has been widely studied in the treatment of seasonal depression (or SAD, seasonal affective disorder). There is more limited research on light therapy for depression that is not seasonal in pattern.
Seasonal depression or seasonal affective disorder (SAD)
- This is a form of depression where periods of depression typically start at certain times of year (for most persons fall/winter but for a smaller group summer) and then improve without treatment when the season changes (for example when spring comes).
- Depression is only considered to be SAD if this has occurred twice in a two year period.
- If there are periods of depression at other times of year, the number of seasonal episodes outnumbers non-seasonal episodes over the person’s lifetime.
- Depression is not considered to be seasonal if the mood change is better explained by seasonally-linked stressors such as seasonal unemployment or school or work stress.
- Common symptoms of SAD include reduced energy, excessive sleeping, excessive eating, weight gain and a craving for carbohydrates (such as sweets, snack foods, breads).
Light therapy for seasonal depression (SAD)
- Light therapy has been shown in a number of well-designed studies to be as helpful as several common antidepressant medications in the treatment of seasonal depression
- It has also been shown in one study to be as helpful as a form of group cognitive behavioral therapy (CBT) developed for seasonal depression. In this study, persons who had combined light therapy and CBT showed the greatest improvement. Persons who had CBT for seasonal depression were less likely to have depression in the risk period in the next year than those treated with light therapy alone.
- Improvement comes more quickly with light therapy than for medication therapy for seasonal affective disorder.
- The benefits of light therapy only continue while the therapy continues. When the light therapy stops, depression often returns. It is usually recommended that the treatment continue until the end of the season in which the person is at risk for depression.
- It is also recommended that light therapy be started at the first signs of depression in the next year during the risk period (usually beginning in September or October in the northern hemisphere). There is less research on light therapy to prevent seasonal depression.
- Light therapy is often combined with medication treatment (which can also be effective as a treatment for seasonal depression on its own). Research shows that it can be effective to have a number of weeks of light therapy during which an antidepressant medication is started, in order to reduce the risk of a return of depression when the light therapy is stopped. Once the medication has been at the right dose for at least four weeks and the depression is well controlled, it may be possible to stop the light therapy without the return of depression. You should discuss the advantages and disadvantages of this approach with your doctor.
Light therapy for depression that does not follow a seasonal pattern
- There are a smaller number of studies on light therapy for non-seasonal depression.
- In these studies light therapy was shown to be as effective as antidepressant medications widely used for depression.
- The effect only continues while the light therapy continues.
- There has also been a small amount of research on light therapy as an add-on to treatment with antidepressant medications. These studies suggest that light therapy resulted in more improvement in depression than medication treatment alone.
Considering treatment with light therapy
- If you are considering treatment with light therapy, it is important to discuss this with your doctor. Your doctor may be able to advise you on which treatment would be most helpful.
- If your doctor is not familiar with this treatment, he or she may be able to refer you to a specialist who can advise you.
- Having the right light source is important. It is most often recommended that people use a light source of 5,000 lux (for one hour) to 10,000 lux (for half an hour) of full spectrum light. This is much brighter than most indoor lighting but not as bright as natural outdoor light (100,000 lux on a sunny day, 20,000 in the shade on a sunny day).
- It is not necessary to look directly at the light but the eyes must be open and the light must be able to reach the eyes. It is recommended that the light be about 60 to 80 centimeters (24 to 32 inches) from the face.
- The 30 to 60 minutes recommended should be daily on an ongoing basis – usually early in the day. This is a significant commitment. It is important to decide whether you can make this commitment in order to use the treatment effectively.
- Morning light is best for most people but evening is more helpful for a smaller group of people.
- It probably works best to pick a time of the morning that fits well with your schedule. People may eat breakfast, read, exercise, or listen to radio or music while they are doing the light therapy.
- Lights for this treatment may be purchased or built for this purpose. In some locations these lights are available for rental or loan (possibly from the local mood disorders association). Some people borrow or rent lights to see if they are helpful before they decide if they wish to purchase them. Some large retailers, including large pharmacies that handle electronic equipment, sell these lights.
- Side effects are described as rare; the most common ones are headache, eyestrain, nausea and agitation. Often these side effects will clear up over time or improve with a reduction in the amount of light used or the time.
Cautions about using light therapy
- Persons with serious eye diseases (such as retinal disease or macular degeneration) or who use medications that cause increased sensitivity to light should not use light therapy unless they have been advised to do so by a doctor.
- If you have bipolar disorder you should seek medical advice before starting light therapy. As with medication treatments of depression, if a person with a history of bipolar disorder uses light therapy there is a modest risk of starting a period of abnormally high mood (hypomania or mania).
Disclaimer: Information in this pamphlet is offered ‘as is’ and is meant only to provide general information that supplements, but does not replace the information from your health provider. Always contact a qualified health professional for further information in your specific situation or circumstance.
You are free to copy and distribute this material in its entirety as long as 1) this material is not used in any way that suggests we endorse you or your use of the material, 2) this material is not used for commercial purposes (non-commercial), 3) this material is not altered in any way (no derivative works). View full license at http://creativecommons.org/licenses/by-nc-nd/2.5/ca/
Source: This summary provides scientifically accurate information. It was prepared in a research review by researchers and young adults with the Mobilizing Minds Research Group. The researchers are based at six universities: Manitoba, York, McMaster, Brock, Brandon, and Université Laval. Our core community partner is mindyourmind.ca located in London, Ontario. Our young adult team members are located all across the country. Last revised: 8 January 2014.
Acknowledgement: Preparation of this material was supported by funding from the Canadian Institutes of Health Research and the Mental Health Commission of Canada. The views expressed here do not necessarily represent the views of these organizations.
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