Medically reviewed by Drugs.com. Last updated on Jan 29, 2021.
Light therapy is a way to treat seasonal affective disorder (SAD) and certain other conditions by exposure to artificial light. SAD 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 and sleep, easing SAD symptoms. Using a light therapy box may also help with other types of depression, sleep disorders and 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:
- Your doctor recommends it for seasonal affective disorder or another condition.
- 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 need to avoid antidepressant medications during pregnancy or while breast-feeding.
- It may allow you to take a lower dose of antidepressant medication.
Conditions it's used for
Light therapy is used as a treatment for several conditions, including:
- Types of depression that don't occur seasonally
- Jet lag
- Sleep disorders
- Adjusting to a nighttime work schedule
Light therapy used to treat skin conditions such as psoriasis is different from the type of light therapy used for the conditions listed above. Light therapy for skin disorders uses a lamp that emits ultraviolet (UV) light. This type of light should be filtered out in light therapy boxes used for SAD and other conditions because it can damage your eyes and skin.
Light therapy is generally safe. If side effects occur, they're usually mild and short lasting. They may include:
- Irritability or agitation
- Mania, euphoria, hyperactivity or agitation associated with bipolar disorder
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 advice if side effects are a problem.
When to use caution
It's best to be under the care of a health professional while using light box therapy. It's always a good idea to talk to a doctor before starting light therapy, but it's especially important if:
- You have a condition that makes your skin especially sensitive to light, such as systemic lupus erythematosus
- You take medications that increase your sensitivity to sunlight, such as certain antibiotics, anti-inflammatories or the herbal supplement St. John's Wort
- You have an eye condition that makes your eyes vulnerable to light damage
Light therapy boxes should be designed to filter out harmful ultraviolet (UV) light, but some may not filter it all out. UV light can cause skin and eye damage. Look for a light therapy box that emits as little UV light as possible. If you have concerns about light therapy and your skin, talk to your dermatologist.
Tanning beds: Not an alternative
Some people claim that tanning beds help ease seasonal affective disorder symptoms. But this hasn't been proved to work. The UV light released by tanning beds can damage your skin and greatly increase your risk of skin cancer.
Caution for bipolar disorder
Light therapy may trigger mania in some people with bipolar disorder, so get advice from your doctor before starting light therapy. If you have any concerns about how light therapy may be affecting your mood or thoughts, seek help right away.
How you prepare
Although you don't need a prescription to buy a light therapy box, it's best to ask your doctor or mental health provider if light therapy is a good option for you. Ask whether you need to take any special precautions. Also discuss which type of light therapy box would best meet your needs, so you get the most benefit and minimize possible side effects.
Internet retailers, drugstores and other stores offer a variety of light therapy boxes. Familiarize yourself with the variety of features and options available on light boxes to help ensure that you buy a high-quality product that's safe and effective. Health insurance companies rarely cover the cost.
What you can expect
Starting light therapy
Generally, most people with seasonal affective disorder begin treatment with light therapy in the early fall, when it typically becomes cloudy in many regions of the country. Treatment usually continues until spring, when outdoor light alone is sufficient to sustain a good mood and higher levels of energy.
If you typically have fall and winter depression, you may notice symptoms during prolonged periods of cloudy or rainy weather during other seasons. You and your doctor can adjust your light 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. Be sure to follow your doctor's recommendations and the manufacturer's directions.
Light therapy requires time and consistency. You can set your light box on a table or desk in your home or office. That way you can read, use a computer, write, watch TV, talk on the phone or eat while having light therapy. Stick to your therapy schedule and don't overdo it.
Three key elements for effectiveness
Light therapy is most effective when you have the proper combination of light intensity, duration and timing.
- Intensity. The intensity of the light box is recorded in lux, which is a measure of the amount of light you receive. For SAD, the typical recommendation is to use a 10,000-lux light box at a distance of about 16 to 24 inches (41 to 61 centimeters) from your face.
- Duration. With a 10,000-lux light box, light therapy typically involves daily sessions of about 20 to 30 minutes. But a lower-intensity light box, such as 2,500 lux, may require longer sessions. Check the manufacturer's guidelines and follow your doctor's instructions. He or she may suggest you start with shorter sessions and gradually increase the time.
- Timing. For most people, light therapy is most effective when it's done early in the morning, after you first wake up. Your doctor can help you determine the light therapy schedule that works best.
Light therapy probably won't cure seasonal affective disorder, nonseasonal 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.
- Get the right light box. Do some research and talk to your doctor before buying a light therapy box. That way you can be sure your light box is safe, the proper brightness, the right kind of light, and that its style and features make it convenient to use.
- Be consistent. Stick to a daily routine of light therapy sessions to 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.
- Track the timing. If you interrupt light therapy during the winter months or stop too soon in the spring when you're improving, your symptoms could return. Keep track of when you start light box therapy in the fall and when you stop in the spring so you know when to start and end your light therapy the following year.
- 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 antidepressants or psychotherapy.