Depression is a state of low mood and not wanting to do anything. It can change what a person thinks, does, feels, and sense of well-being. It may lead to being sad, make it harder to think and a large change in appetite and time spent sleeping. People who have depression may feel no hope and, sometimes, thoughts of suicide. It can either be short term or long term. The main symptom of depression is said to be anhedonia, which means losing of interest in things that usually make people happy. Depressed mood is a symptom of some mood disorders such as major depressive disorder or dysthymia; it is a normal reaction to life events, such as losing a loved one; and it is also caused by some physical diseases and a side effect of some drugs and medical treatments.