‘Tis the season of darkness. The clocks are turned back, the biological clock on those pretty leaves outside is a-tickin’, and soon it will be nothing but bare branches and 4:45 p.m. sunsets. This is a certifiable bummer for all of us in the Northern Hemisphere, but for people who suffer from Seasonal Affective Disorder, it's worse: As the sun goes, so too goes their mental health.

For many with SAD, this means dragging out the light-therapy lamp. Light therapy is the most researched and widely-used treatment for SAD. It requires a person to sit under a very bright light for 30 minutes upon waking, every day that he or she would have symptoms.

But according to a new study funded by the National Institute of Mental Health and published in The American Journal of Psychiatry, cognitive behavioral therapy could be better for patients in the long run than light therapy. In the largest randomized trial to date on this, the researchers followed 177 people as they underwent light therapy or CBT tailored for SAD for six weeks, then checked back in with them during the subsequent two winters.

That first winter, CBT and light therapy worked pretty much equally well at reducing people’s depressive symptoms and putting their SAD into remission. And they were evenly matched at the first follow-up appointment, too. But by the second follow-up appointment, CBT had pulled ahead. Among the group that got CBT, 27.3 percent had their depression come back the second winter, compared to 45.6 percent of those who got light therapy, and symptoms were less severe for the people in the CBT group as well. Even after the researchers controlled for any other treatments the patients might have tried in the meantime, the difference between the CBT group and the light-therapy group remained.