Let’s be honest: The so-called “most wonderful time of the year” sometimes seems like it’s anything but. It’s freezing outside. And, ugh, why does the sun disappear at 5 o’clock in the afternoon?If all this sounds familiar, you might be wondering whether you have a case of the winter blues — or, more seriously, seasonal affective disorder . Known by its fitting acronym, SAD, this condition used to occupy its own turf in the Diagnostic and Statistical Manual, a kind of Bible-esque book for psychologists and mental-health experts. Now, however, seasonal affective disorder is considered to be a subset of major depression, says Sabrina Brem, a family nurse practitioner and assistant professor at the Columbia University School of Nursing, whose research focuses on anxiety and depression.“You have to meet certain criteria to be diagnosed,” she explains. Not only do you have to exhibit symptoms of depression — i.e., feeling depressed most of the time, experiencing feelings of worthlessness and hopelessness, and more — but those symptoms also have to coincide with a particular season, like the winter months. And they have to recur year after year.It’s hard to know for sure how many people actually have SAD — statistics are hard to come by — but a 2012 paper in the American Family Physician says that in the United States, its prevalence might range from about 1 to 2% of the population. Plus, the verdict is still out on what causes the disorder; the best guess is that the dwindling amount of sunlight during the winter throws off some people's circadian rhythms, triggering those depressive symptoms. But some experts question whether it’s a real phenomenon at all Even if you don’t have SAD (and you probably don’t), it’s still possible for the happiest time of year to bum you the hell out, Brem says.Thing is, regardless of whether you are depressed or just struggling with the winter sads, it might be hard to tell the difference. Talking to a doctor or a therapist can help. You should never feel ashamed if you’re really feeling down. Know that help is out there. And if you’re just looking for ways to get through this dark, cold hell of a season (sequined New Year's Eve dresses be damned!), here are 30 small changes you can make to your habits that may help lift your spirits while you're waiting for spring.