According to the American Psychiatric Association, at least one in six adults will experience depression in their lifetime. Depression symptoms range from mild to severe.
At least five of these symptoms must occur over a two week period or more and are a previous change in functioning:
disinterest in daily activities
hopelessness
feeling tired during the day
poor sleep or excessive sleep
negative thoughts about oneself, others, and the world
difficulty concentrating
feeling sad
changes in appetite (increase or decrease)
feeling worthless or negative attitude towards oneself
restlessness
slowed speech, movements
thoughts of death or suicide