REM sleep and mental disorders on the 70th anniversary of the discovery of REM sleep.

The discovery of rapid eye movement sleep in 1953 led to numerous studies investigating the relationship between rapid eye movement sleep abnormalities and psychiatric disorders. The most salient findings were the association of rapid eye movement sleep alterations-reduced rapid eye movement sleep latency, increased rapid eye movement sleep volume of total sleep, and increased rapid eye movement density-with major depression. This paper briefly reviews the history of rapid eye movement sleep research in psychiatry with a focus on the work related to major depressive disorder and some of the various theories that have been proposed to explain the associated rapid eye movement sleep abnormalities. Given the increasing evidence that rapid eye movement sleep is important for emotional processing, memory and cognition, a better understanding of the underlying mechanisms for the relationship between rapid eye movement sleep and mood disorders could lead to improved treatments for these common and disabling illnesses.