We've all heard of seasonal affective disorder, but did you know that it's more than just the winter blues? The cooler temperatures, seasonal changes, and limited daylight hours of the winter months can stir up a certain cozy feeling, but they can also bring a sense of lethargy, persistent sadness, and a loss of interest in activities that once brought joy. So, what exactly is seasonal affective disorder? What are the symptoms? Are there effective treatments available? We spoke with Michael Terman, PhD, founder and president of the Center for Environmental Therapeutics, about the science behind what causes seasonal affective disorder, the significant role that your chronotype plays, where and how to accurately assess mood changes during seasonal transitions, and the therapies available that alleviate symptoms associated with seasonal affective disorder.