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Light Therapy

Other common name(s): light boxes, bright light treatment, ultraviolet light therapy, UV, ultraviolet blood irradiation, colored light therapy, chromatotherapy

Scientific/medical name(s): phototherapy, ultraviolet phototherapy, photopheresis, extracorporeal photochemotherapy, photodynamic therapy


Light therapy involves the use of visible light or non-visible ultraviolet light to treat a variety of conditions.


Some forms of light therapy, such as light boxes, ultraviolet (UV) light therapy, and photodynamic therapy, are used in mainstream medicine. However, available scientific evidence does not support claims that alternative uses of light or color therapy are effective in treating cancer or curing other illnesses.

How is it promoted for use?

Mainstream medical professionals may prescribe the use of light boxes, photopheresis, photodynamic therapy, or UV light therapy. These are typically used to treat conditions for which studies have shown the methods to be safe and effective. For example, the use of light boxes to mimic sunlight is a proven medical treatment for seasonal affective disorder (SAD). Ultraviolet (UV) light therapy is used to treat psoriasis and cutaneous T-cell lymphoma (a type of cancer that first appears on the skin). Photodynamic therapy is helpful in treating certain cancers or precancers of the skin, esophagus, and lungs, and is now being tested against other types of cancer. A special form of UV blood irradiation, called photopheresis or extracorporeal photochemotherapy, also inhibits T-cell lymphoma and may be helpful for other conditions.

However, several types of light therapy are also promoted for alternative uses. These include light boxes (or special bright lamps and visors), UV light or sun lamp therapy, most types of colored light therapy (chromatotherapy), and UV blood irradiation. There are also colored glasses that a person can wear so that they see a certain color in every type of light.

Colored light therapy: Supporters of colored light therapy (also called chromatotherapy) claim that colored light relieves a number of conditions, including sleep disorders, shoulder pain, diabetes, impotence, and allergies. Others believe that it can help colds and flu, stress, fatigue, high blood pressure, as well as heart and lung problems. Practitioners of one system of chromatotherapy believe that shining colored lights on the body harms cancer cells.

Light box therapy: Light box therapy is also sometimes called bright light therapy and can employ light boxes, bright lamps, or light visors. Proponents claim it relieves high blood pressure, insomnia, premenstrual syndrome, migraine headaches, carbohydrate cravings, hyperactivity in children, and that it improves sexual functioning.

UV light: Proponents of UV light therapy, which is sometimes marketed as sun lamps, claim that it neutralizes toxins in the body and cures or helps immune system disorders, bacterial infections, AIDS, colds, bug bites, and cancer.

UV blood irradiation: Proponents of UV blood irradiation claim that UV light exposure kills germs such as viruses, bacteria, and fungi inside the body and that it neutralizes toxins in the blood. Some claim that even a small amount of UV-treated blood can re-enter the bloodstream of the patient and stimulate the immune system to help fight invaders, including cancer cells.

What does it involve?

Colored light therapy involves the use of colored lights such as blue, red, and violet lights that the practitioner shines directly on the patient. In some cases, the patient purchases the device and uses it at home in this alternative use of light therapy. Sometimes the lights flash in patterns.

A newer way of getting the colored light therapy is via internet, using a computer monitor for the color output. A "color session" of variable length and composition is offered to the user from the comfort of their own home or desk. This particular alternative use says that the person is not required to even watch the screen, as long as he or she stays in the room with the computer monitor. Most sessions take less than half an hour. There is no limit on the number of treatments a person can take.

Another way of getting light therapy involves using colored sunglasses to tint everything the wearer sees with the desired color. Books and charts are available to tell the user how to use these alternative therapy devices.

One type of light therapy is used in conventional medicine for newborns who have a buildup of a waste product called bilirubin in the blood. The infant's skin is exposed to a special blue light, usually for several days. This helps the bilirubin to break down into a substance that is easier for the baby to excrete.

Light boxes contain lights that simulate the wavelengths of sunlight, and are used in mainstream medicine. Patients getting this kind of treatment sit in front of the light box or special bright lamp for a prescribed amount of time each day. The person may read or do other tasks during the light exposure, but must sit close enough to the light to receive its full effect. The amount of time required will vary according to the person and the strength of light being used. For most people with SAD, light treatment is used early in the morning from thirty minutes to two hours each day. A brighter light may require less time exposure.

In ultraviolet light therapy, the eyes and unaffected skin are protected while the patient is exposed to UV light for a prescribed length of time. This conventional treatment for psoriasis may involve the use of UV light and drugs that make the skin sensitive to UV light. A newer type of UV light, called narrow-band UV light, is also being used now and may work better than broad-band UV light.

Ultraviolet blood irradiation is called photopheresis or extracorporeal photochemotherapy in conventional medicine and is mainly used to inhibit T-cell lymphoma. It may also be helpful for other conditions. During this procedure, blood is removed from the patient and separated into different types of cells. About a pint of blood, mostly white blood cells, is treated with a special drug to make it make it more sensitive to light. It is then treated with UV light, and the blood is infused back into the patient. This procedure is considered a form of immunotherapy and takes from three to five hours.

Something a little like this is offered by some alternative therapists. In those cases, a small tube of blood is removed, treated with UV rays, and infused back into the patient.

Photodynamic therapy is used in conventional medicine for certain types of cancer. The patient is given a drug to make cancer cells more sensitive to light. The tumor area is then exposed to laser or another type of light.

What is the history behind it?

Interest in the relationship between light and health dates back centuries. All forms of light therapy now in use started during the 20th century. The first reports of ultraviolet blood irradiation date back to the 1930s.

What is the evidence?

Light box therapy: Available scientific evidence does not support claims that light box treatments can cure cancer, but it does have some medically accepted uses. Light box therapy has been shown to be effective in treating seasonal affective disorder (SAD), a type of depression caused by insufficient exposure to bright light. Some researchers are testing light therapy to see if it helps other types of depression, but the jury is still out. It may also be helpful for shift workers and those traveling to different time zones in helping to reset their internal clocks.

Ultraviolet light therapy (phototherapy) is commonly used to treat psoriasis. There is also evidence that UV light therapy inhibits the growth of cutaneous T-cell lymphoma (a type of skin lymphoma). Researchers have found that when used along with other treatment, it has resulted in long-term remission and cure among many patients in the early stage of the disease. In patients who were treated later in the disease, it has prolonged survival. Early studies suggest that certain types of UV light may also be helpful for people with atopic dermatitis (an allergic skin condition) and vitiligo (uneven pigment in the skin). However, available scientific evidence does not support other health claims for UV light therapy.

Colored light therapy has been advocated since the early twentieth century for nearly every imaginable purpose. At least one maker of the Spectro-Chrome (color) therapy devices has been prosecuted for making false claims. But a certain type of blue light has been used for years to treat newborns with high bilirubin levels in the blood and has proven to be very effective. At this time, available scientific evidence does not support claims that any other type of colored light therapy is effective in treating cancer or other illnesses.

Ultraviolet blood irradiation treatment is approved by the U.S. Food and Drug Administration (FDA) for treating T-cell lymphoma involving the skin. Photopheresis is sometimes used conventionally when organ transplant rejection or graft-versus-host disease (a complication related to bone marrow or stem cell transplants) does not respond to usual conventional treatments. Some clinical trial results look promising for the treatment of immune system diseases such as multiple sclerosis, systemic sclerosis, rheumatoid arthritis, lupus, and type 1 diabetes. Available scientific evidence does not support claims for alternative uses of UV blood irradiation.

Are there any possible problems or complications?

Light therapy that involves only visible light (light boxes and colored light therapy) is generally considered safe. Light therapy for depressive disorders can push a few people into a hyperactive state called mania, which may pose some risk. Light or light box therapy should not be confused with a tanning bed or sun lamp, which is not a medical therapy and is dangerous because of high levels of ultraviolet radiation. Any treatment that exposes the patient to ultraviolet radiation presents some danger, including premature aging of the skin and an increased risk for skin cancer later in life.

People who get long-term UV light treatment for psoriasis or other conditions may have a greater-than-average number of cataracts and skin-related problems, including cancer. They may also be at higher risk of sunburn the day of UV treatment and are advised to avoid natural sunlight.

Relying on unproven uses of light therapy while delaying or avoiding conventional therapy for cancer can have serious consequences.

To learn more

More information from your American Cancer Society

The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-227-2345).

Dietary Supplements: What Is Safe?

The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management

Complementary and Alternative Methods and Cancer

Placebo Effect

Learning About New Ways to Treat Cancer

Learning About New Ways to Prevent Cancer


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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.

Last Medical Review: 04/14/2011
Last Revised: 04/14/2011