Unless you live in a tropical paradise, chances are that some months of the year are gloomier than others. As autumn and winter roll around, the tilt of the Earth pulls us out of sunlight's direct path, leading to colder temperatures, fewer daylight hours, and more time spent inside. For some people, this can also lead to a period of depression that physicians call seasonal affective disorder, or SAD.
The snappy acronym notwithstanding, SAD is no social media trend—it's a real psychological condition with real drawbacks. According to American Family Physician, about 5% of the U.S. population—as many as 1 in 20—experiences SAD in a given year, and in northern latitudes, that number can climb to 10%. SAD is a form of clinical depression, and its symptoms are similar with two differences: they only affect you seasonally (for 40% of the year, on average), and they can make you crave food more, especially carbohydrates.