Weather often affects people’s moods. Sunlight breaking through clouds can lift our spirits, while a dull, rainy day may make us feel a little gloomy. While noticeable, these shifts in mood generally do not affect our ability to cope with daily life. Some people, however, are vulnerable to a type of depression that follows a seasonal pattern. For them, the shortening days of late autumn are the beginning of a type of clinical depression that can last until spring. This condition is called “Seasonal Affective Disorder,” or SAD.