Bright light therapy may help ease SAD, major depression, and perinatal depression.
The transition from fall to winter means gray skies, shorter days, and for some people, the return of seasonal affective disorder. With the apropos acronym of SAD, this disorder has symptoms similar to depression (such as feeling sad, listless, and lethargic) but occurs only during late fall and early winter.
Light therapy — which involves sitting close to a special light source every morning for at least 30 minutes — may help improve SAD. But many people don’t realize that this therapy can also be effective for major depression and depression that occurs during or after pregnancy, called perinatal depression.
“For both seasonal and non-seasonal depression, the effectiveness of light therapy is approximately the same as that of antidepressant medications or popular forms of psychotherapy such as cognitive behavioral therapy,” says Dr. Richard S. Schwartz says. Although evidence varies from study to study, each of these different treatments reportedly improves symptoms in between 40% and 60% of people. Combining two of these treatments together — light therapy and medications — helps even more.
Why do people experience SAD?
SAD is triggered by a decline in daily sunlight exposure. Light affects the complex systems in the brain that control the 24-hour circadian clock, which regulates not only our sleep-wake cycles but also digestion, hormonal activity and other important bodily functions.
Special receptors in the retina (the light-sensitive part of the eye) transmit information about the light in our surrounding environment to the suprachiasmatic nucleus deep in the brain – this is the body’s master clock. In recent years, scientists have discovered additional neural pathways from the light receptors in the retina to other parts of the brain. This includes the prefrontal cortex, which is involved in regulating mood and cognition, Dr. Schwartz explains.
“Beyond setting our circadian clock, light exposure also affects higher-functioning areas of the brain,” he says. So light therapy may help treat SAD, which, like major depression, can also be treated with medications and therapy.
Light therapy may prompt improvement with few side effects
For both SAD and other types of depression, light therapy has unique characteristics that make it an attractive alternative to drugs, Dr. Schwartz notes. Antidepressant medicines often take several weeks to start working, and sometimes have troubling side effects including nausea, weight gain and sexual dysfunction. In those who respond well to light therapy, symptoms of depression usually begin to improve within a week, and side effects, which include eye strain and headache, are uncommon and mild.
For people with depression who are pregnant or elderly, trying light therapy may make sense because these groups often need to avoid or reduce their use of medication. And older people, especially those with limited mobility, often spend a lot of time in dim environments and are more prone to depression, Dr. Schwartz says.
how to use light therapy
Light therapy requires a light box that emits 10,000 lux (a measure of light intensity). As soon as possible after you wake up every morning, sit in front of the light for about 30 minutes. Light boxes aren’t regulated, so it’s important to make sure you buy a box that meets certain specifications. Doctor. Schwartz recommends checking out the Center for Environmental Therapeutics, a nonprofit organization that researches light boxes and related therapies and provides advice for selecting a light box. Prices range between $100 and $200.
To use a light box, hold it in front of you or slightly to the side. Do not look directly at the light, but keep your eyes open. You can eat, read, watch TV, or work on the computer while the light is on.
Doctor. People who have bipolar disorder should consult with a psychiatrist or other mental health professional before trying light therapy, says Schwartz. In rare cases, therapy may trigger a manic episode, a risk that is possible even when first starting antidepressants. Even people with severe depression should not attempt light therapy without the guidance of a psychiatrist.
For everyone who is feeling down or depressed — whether or not related to the weather or pregnancy — a morning walk can provide similar light therapy benefits. A bright sunny day is about 50,000 lux, and a gray day is about 10,000 lux. “A walk outside shortly after sunrise, even on a cloudy day, provides roughly the same amount of light exposure as a light box,” says Dr. Schwartz.
On sunny days, the sun is bright enough to have a therapeutic effect even if you wear sunglasses (which protect your eyes from the sun’s ultraviolet radiation). If you walk for 30 minutes, you’ll also get a healthy dose of mood-boosting exercise. But if time or a lack of mobility make that goal too challenging, just sitting outside for 15 minutes at any time of day can make a difference in your mood, Dr. Schwartz says.