Depression

A psychological condition characterized by feelings of sadness, emptiness and hopelessness, diminished concentration, loss of pleasure in daily activities, fatigue, insomnia and thoughts of suicide. While these feelings are transient in normal people, depressed individuals experience these symptoms for long periods of time-over two weeks- and are significantly impaired by their symptoms. Depression can negatively affect quality of life and may even cost patients their social, work and family relationships. 

Cannabis has been shown to alleviate symptoms or depression.