Light therapy is a way to treat seasonal affective disorder, depression, shift work disorder and certain other conditions by exposure to bright artificial light. During light therapy, you sit or work near a device called a light therapy box.
The light therapy box gives off bright light that mimics natural outdoor light.
Exposure to bright light from a light therapy box is thought to alter your circadian rhythms and suppress your body's natural release of melatonin.
Together, these cause biochemical changes in your brain that help reduce or control symptoms of seasonal affective disorder and other conditions. Light therapy is also known as bright light therapy or phototherapy.
The light box used in light therapy emits a type and intensity of light that isn't found in normal household lighting. So simply sitting in front of a lamp in your living room is unlikely to relieve your seasonal affective disorder symptoms or other problems.
Similarly, a light box delivers brighter, more focused light than you can find outdoors, which makes it more effective than trying to get enough light exposure by spending time outside — especially on gloomy days.
Risks and side effects associated with light therapy are uncommon but can happen. When side effects do occur, they're usually mild. They may go away on their own within a few days of starting light therapy.
You also may be able to manage these problems 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.
During light therapy sessions, you sit or work near a light therapy box. To be effective, the 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 light can damage your eyes.
Three key elements for effective light therapy
Light therapy is most effective when you have the proper combination of duration, timing and light intensity:
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, your light therapy typically involves daily sessions ranging from 30 minutes to two hours, depending on your light box's intensity.
For people using light therapy for treatment of seasonal affective disorder (SAD), light therapy is most effective if used in the morning, after you first wake up.
If you are using light therapy to boost your alertness while working night shift, light therapy is most effective if used between midnight and 4 a.m. Be cautious too much light late in your shift can delay sleep onset when you are trying to sleep.
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, with 10,000 lux being typical. In contrast, the lighting in an average living room in the evening is less than 400 lux, while a bright sunny day may register 100,000 lux.
The intensity of your light box may also determine 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 is still open to debate.