With the coming of winter, and shorter days and longer nights, many people suffer from seasonal affective disorder, a type of depression connected to the changing of seasons and decrease in natural light that’s estimated to affect about 10 million Americans.

As the sun’s rays retreat, many turn to light therapy, relying on artificial light emitted by specially made equipment or light boxes to address the seasonal mood disorder. Research from around the world shows this longstanding treatment is effective for winter depression, says Kelly Rohan, a professor of psychology science at the University of Vermont.

Seeing the Light in Treating SAD

Light therapy – also sometimes called bright light therapy or phototherapy – is typically administered at home, though it's also offered by some health clubs. It involves sitting in front of a light therapy device that’s angled to simulate natural sunlight. The light enters the eye, hitting the retina. There's debate as to why seeing the light, so to speak, works: One prevailing theory is that doing so helps reset a person's circadian rhythm or biological clock; but some experts theorize it's the therapy's effect on neurotransmitters in the brain associated with pleasure, like dopamine, which improve mood.

In addition, many different products are available. In her research, Rohan says she uses a light box that's about the size of a large computer monitor, which emits 10,000 lux, a measure of illuminance, of cool white fluorescent or full-spectrum light to optimize exposure with a built-in screen to filter out harmful ultraviolet rays.

Most mental health professionals view light therapy as the leading choice to treat seasonal affective disorder. “However, there are plenty of reasons to look for alternative treatment,” Rohan says. She notes that about half of those treated with light therapy experience remission from SAD – or get better – “which is great if you’re within the 50 percent that gets better, but not such good news if you’re in the other 50 percent.”

But perhaps the most compelling reason to consider alternative treatments to light therapy, she adds, is that many people aren’t able to stick with it. That's because, for one thing, the therapy is time-intensive. Most people require at least 30 minutes of light exposure daily and some need 45 minutes or an hour daily to see a benefit, she notes. “Long-term compliance [is] actually quite poor,” Rohan says. In particular, she points to a National Institute of Mental Health research that found 59 percent of people treated with light therapy discontinued it following a research trial. “That’s a problem for a treatment that suppresses symptoms and has to be continued,” she says, when SAD returns each winter.

Other Options for Treating Winter Depression

In research Rohan led comparing light therapy for SAD treatment with cognitive behavioral therapy – which involves learning how to change thoughts and behaviors to cope, in this case, with winter – the results were initially similar. But researchers found that despite the fact that light-therapy participants were advised to continue with daily light therapy, after undergoing six weeks of light therapy, as part of a randomized study trial, many failed to do so. (During the initial six-week treatment period, participants were started on 30 minutes of light each morning, and that treatment duration was adjusted according to an algorithm based on response to treatment and side effects.)

In following the 89 participants initially treated with light therapy and 88 participants who had been treated with CBT during the six-week trial period over the course of two winters, researchers found that by the second winter, seasonal affective disorder had recurred for nearly 46 percent in the light therapy group, compared to 27 percent in the CBT group, who also experienced less severe depressive symptoms. Compared with light therapy, CBT had an enduring effect that reduced the risk of SAD recurrence after initial treatment, the researchers noted in the study published in the American Journal of Psychiatry.

Sanam Hafeez, a clinical neuropsychologist and director of the neuropsychological, developmental and educational center, Comprehensive Consultation Psychological Services, and a professor of psychology at Teachers College, Columbia University in New York City, calls the study a “game changer,” since research on CBT to treat SAD has been scarce. However, she says the results shouldn’t distract from the benefits of light therapy, which is more readily available and cost-effective than CBT.

Light therapy units can be purchased online, the devices aren’t regulated by the Food and Drug Administration and they don’t require a prescription. Units like those Rohan uses in her research, the most widely tested in clinical trials for SAD, generally cost between $150 and $350, she says.

Though the devices are easy to acquire, their use is not without risk. Side effects are generally milder than those that accompany antidepressant medications, which can also be used to treat seasonal affective disorder, "but people can still have things like mild headaches or blurred vision or eye strain,” says Dr. Raymond Lam, a professor of psychiatry at the University of British Columbia in Vancouver. “Because the light is activating or energizing, some people find it’s a bit agitating.” Sometimes more serious issues occur, including an increase in suicidal thoughts, Rohan says.

A recent study Lam led, published in the journal JAMA Psychiatry in January, found that light therapy is also effective in treating nonseasonal depression, and that light therapy plus medication – in this case, Prozac – was more effective in treating major depression than either treatment alone.

Guided Therapy

If you think you suffer from seasonal affective disorder, seek professional help before making treatment decisions, experts say. “Avoid self-diagnosis,” Rohan cautions. “Go see a qualified mental health professional to make sure that this really is winter depression” – as opposed to another mental health disorder or the result of an underlying medical condition.