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Light therapy
By Mayo Clinic staffOriginal Article: http://www.mayoclinic.com/health/light-therapy/MY00195
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Definition
Light therapy is a way to treat seasonal affective disorder (SAD) by exposure to artificial light. Seasonal affective disorder is a type of depression that occurs at a certain time each year, usually in the fall or winter.
During light therapy, you sit or work near a device called a light therapy box. The box gives off bright light that mimics natural outdoor light. Light therapy is thought to affect brain chemicals linked to mood, easing SAD symptoms. Using a light therapy box may also help with other types of depression, sleep disorders and some other conditions. Light therapy is also known as bright light therapy or phototherapy.
Why it's done
You may want to try light therapy for a number of reasons:
- It's a proven seasonal affective disorder treatment.
- You have another condition, such as nonseasonal depression or insomnia, and your doctor recommends it.
- You want to try treatment that is safe and has few side effects.
- You want to increase the effectiveness of antidepressant medication or mental health counseling (psychotherapy).
- You can't take antidepressant medications during pregnancy or while breast-feeding.
- It may allow you to take a lower dose of antidepressant medication.
Light therapy for conditions other than SAD
In addition to seasonal affective disorder, light therapy is being studied as a treatment for other conditions, including:
- Types of depression that don't occur seasonally
- Obsessive-compulsive disorders
- Jet lag
- Sleep disorders
- Adjusting to a nighttime work schedule
- Parkinson's disease
- Dementia
- Attention-deficit/hyperactivity disorder (ADHD)
Light therapy is also used to treat skin conditions such as psoriasis. However, this is different from the type of light therapy used for seasonal affective disorder and the other conditions above. Light therapy for skin disorders uses a lamp that emits ultraviolet (UV) light. This type of light is filtered out in light therapy boxes because it can damage the eyes and skin.
Risks
Light therapy is generally safe. Side effects are generally mild and short-lasting when they do occur. They can include:
- Headache
- Nausea
- Eyestrain
- Irritability or agitation
- Mania, euphoria, hyperactivity, or agitation associated with bipolar disorder
- Dry mouth
- Sleep problems
When side effects do occur, they may go away on their own within a few days of starting light therapy. You also may be able to manage side effects by reducing treatment time, moving farther from your light box, taking breaks during long sessions, or changing the time of day you use light therapy. Talk to your doctor for additional help and advice, or if side effects don't go away or get worse.
When to use caution
It's always a good idea to talk to a doctor before starting light therapy. But it's especially important to consult your doctor first if:
- You have a condition that makes your skin especially sensitive to light, such as systemic lupus erythematosus (SLE)
- You take medications that increase your sensitivity to sunlight, such as certain antibiotics, anti-inflammatories and the herbal supplement St. John's Wort
- You have an eye condition that makes your eyes vulnerable to light damage
- You have a history of skin cancer
Ultraviolet light
Although light therapy boxes are designed to filter out harmful ultraviolet (UV) light, some may not filter it all out. This type of light can cause skin and eye damage. Look for a light therapy box that emits as little UV light as possible.
Tanning beds: Not an alternative to light therapy
Some people claim that tanning beds help ease seasonal affective disorder symptoms. But this hasn't been proven to work. Visible light, not the UV light released by tanning beds, is used in light therapy. The type of light released by tanning beds can damage your skin and may increase your risk of skin cancer.
Cautions for bipolar disorder and severe depression
Light therapy may trigger mania in some people with bipolar disorder. Also, there have been some cases in which light therapy seemed to cause suicidal thoughts. If you have any concerns about how light therapy may be affecting your mood or thoughts, seek help right away.
How you prepare
Before starting light therapy, check with your doctor and mental health provider to be sure that light therapy is a good option for you, and to find out whether you need to take any special precautions.
Internet retailers, drugstores and even some hardware stores offer a variety of light therapy boxes. Or your doctor may prescribe a particular light therapy box. In some cases, health insurance companies require a prescription from a doctor to cover the cost of a light therapy box. Talk with your doctor about the best light therapy box for you, and familiarize yourself with the variety of features and options to help ensure that you buy one that is safe and effective for you.
Although it's possible to do light therapy on your own, it's best have the guidance of a doctor or mental health provider. This can help you get the most benefit out of light therapy and minimize possible side effects.
What you can expect
Starting light therapy
The general recommendation for most people with seasonal affective disorder is to begin treatment with light therapy in the early fall. Treatment generally continues until spring, when outdoor light alone is sufficient to sustain a good mood and higher levels of energy.
Some people experience seasonal affective disorder in the summer. And others who typically have winter depression may notice symptoms during prolonged periods of cloudy or rainy weather during other seasons. You and your doctor can adjust your light box treatment based on the timing and duration of your symptoms.
If you want to try light therapy for nonseasonal depression or another condition, talk to your doctor about how light therapy can be most effective.
During light therapy
During light therapy sessions, you sit or work near a light box. To be effective, light from the light box must enter your eyes indirectly. You can't get the same effect merely by exposing your skin to the light. While your eyes must be open, don't look directly at the light box, because the bright light can damage your eyes.
Light therapy sessions are generally done each morning after you wake up. Some light therapy boxes, however, are dawn simulators — they turn on in the morning while you're still asleep and gradually get brighter until you wake up.
Three key elements for effective light therapy
Light therapy is most effective when you have the proper combination of duration, timing and light intensity:
- Duration. When you first start light therapy, your doctor may recommend treatment for shorter blocks of time, such as 15 minutes. You gradually work up to longer periods. Eventually, light therapy typically involves daily sessions ranging from 30 minutes to two hours, depending on your light box's intensity.
- Timing. For most people, light therapy is most effective when it's done early in the morning, after you first wake up. Doing light therapy at night can disrupt your sleep. Because light therapy seems to work best in the early morning, you may need to wake up earlier than you normally would to get the most benefit from treatment. Your doctor can help you find the light therapy schedule that works best.
- Intensity. The intensity of the light box is recorded in lux, which is a measure of the amount of light you receive at a specific distance from a light source. Light boxes for light therapy usually produce between 2,500 lux and 10,000 lux. The intensity of your light box affect how far you sit from it and the length of time you need to use it. The 10,000 lux light boxes usually require 30-minute sessions, while the 2,500 lux light boxes may require 2-hour sessions.
Finding time for light therapy
Light therapy requires time and consistency. You may be tempted to skip sessions or quit altogether because you don't want to spend time sitting by a light box. But light therapy doesn't have to be boring. It can be time well spent.
You can set your light box on a table or desk in your home or in your office. That enables you to read, use a computer, write, watch television, talk on the phone or eat while undergoing light therapy. Some light boxes are even available as visors that you can wear, although their effectiveness isn't proven.
Results
Light therapy probably won't cure seasonal affective disorder, depression or other conditions. But it may ease symptoms, increase your energy levels and help you feel better about yourself and life.
Light therapy can start to improve symptoms within just a few days. In some cases, though, it can take two or more weeks.
Getting the most out of light therapy
Light therapy isn't effective for everyone. But you can take steps to get the most out of your light therapy and help make it a success, including:
- Be consistent. Sticking to a daily routine of light therapy sessions can help ensure that you maintain improvements over time. If you simply can't do light therapy every day, take a day or two off, but monitor your mood and other symptoms — you may have to find a way to fit in light therapy every day.
- Time it right. If you interrupt light therapy during the winter months or stop too soon in the spring when you think you're improving, your symptoms could return.
- Get the right light box. Do some research and talk to your doctor before purchasing a light therapy box. That way you can be sure your light box is safe, the right brightness and that its style and features make it convenient to use.
- Include other treatment. If your symptoms don't improve enough with light therapy, you may need additional treatment. Talk to your doctor about other treatment options, such as psychotherapy or antidepressants.
- Rosenthal NE, et al. Light therapy. In: Gabbard GO, et al. Treatments of Psychiatric Disorders. 4th ed.: American Psychiatric Publishing; 2007. http://www.psychiatryonline.com/content.aspx?aID=257853. Accessed July 13, 2010.
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- Practice guideline for the treatment of patients with major depressive disorder. 2nd ed. American Psychiatric Association. http://www.psychiatryonline.com/content.aspx?aID=49541&searchStr=phototherapy#49541. Accessed July 13, 2010.
- Howland RH. Somatic therapies for seasonal affective disorder. Journal of Psychological Nursing. 2009;47:17.
- Sivamani RK, et al. The benefits and risks of ultraviolet tanning and its alternatives: The role of prudent sun exposure. Dermatologic Clinics. 2009;27:129.
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