• In the treatment of endogenous depression by rapid eye movement (REM) sleep deprivation, depression improvement, measured on Hamilton and Global scales, correlated positively and significantly (P <.05) with REM pressure (increase of REM sleep stimulated by REM sleep deprivation). This dose-response relationship suggests that (1) REM pressure was an indicator of a process that mediated the antidepressant effects of REM sleep deprivation, and (2) since improvement varied with stimulation of REM sleep, an unknown stimulus of REM sleep is a naturally occurring, endogenous antidepressant.
Vogel GW, McAbee R, Barker K, Thurmond A. Endogenous Depression Improvement and REM Pressure. Arch Gen Psychiatry. 1977;34(1):96-97. doi:10.1001/archpsyc.1977.01770130098010