Recent research shows that the depression symptoms associated with seasonal affective disorder (SAD) can be greatly influenced by gut health. Eating foods rich in probiotics—such as sauerkraut, kimchi, and kefir—as well as prebiotics, such as Jerusalem artichokes and jicama, may strengthen your microbiome, says Raphael Kellman, M.D., founder of the Kellman Center for Integrative and Functional Medicine and author of The Microbiome Diet. That in turn can have positive effects on mood and a significant impact on relieving symptoms of SAD.

Watch out: A few surprising foods may make symptoms worse, including dried or canned fruits, juices, potatoes, and sweet potatoes—all of which feed glucose and/or starch to unhealthy bacteria.