Major depressive disorder is only one type of depressive disorder. Other types include: Seasonal Affective Disorder (SAD) – This type of depression is directly caused by the time of the year. It occurs most often in the winter months when people have access to less sunlight, typically going away in the spring and summer. Persistent Depressive Disorder – This is depression that lasts for two years or longer. Psychotic Depression – This is depression accompanied by psychotic symptoms such as hallucinations, delusions, and paranoia. Postpartum Depression – This is depression that develops in the weeks or months after childbirth. Premenstrual Dysphoric Disorder (PMDD) – This is depression experienced by women prior to the start of each period. It often occurs with symptoms such as fatigue, anxiety, mood swings, changes in appetite, changes in sleep patterns, difficulty concentrating, irritability, and feeling overwhelmed. Situational Depression – This is a short-term, typically stress-related type of depression that develops in response to a traumatic event. Common events that can trigger situational depression include the death of a loved one, divorce, and illness. Situational depression is also called “stress response syndrome.”