Editing Rapid eye movement sleep (section)

==== Brain stem ====
Neural activity during REM sleep seems to originate in the [[brain stem]], especially the [[pontine tegmentum]] and [[locus coeruleus]]. REM sleep is punctuated and immediately preceded by [[PGO waves|PGO (ponto-geniculo-occipital) waves]], bursts of electrical activity originating in the brain stem.<ref name="Steriade_2013" />{{rp|§9.1–2 263–282}} (PGO waves have long been measured directly in cats but not in humans because of constraints on experimentation; however, comparable effects have been observed in humans during "phasic" events which occur during REM sleep, and the existence of similar PGO waves is thus inferred.)<ref name=EPS2011 /> These waves occur in clusters about every 6 seconds for 1–2 minutes during the transition from deep to paradoxical sleep.<ref name="Steriade_2013" /> They exhibit their highest amplitude upon moving into the [[visual cortex]] and are a cause of the "rapid eye movements" in paradoxical sleep.<ref name=Datta>{{cite book | vauthors = Datta S | chapter = PGO Wave Generation: Mechanism and functional significance | title = Rapid Eye Movement Sleep | date = 1999 | pages = 91–106 }}</ref><ref name=ErmisEtAl /><ref name=HobsonEtAl2000 /> Other muscles may also contract under the influence of these waves.<ref name=Siegel2009 />