A team of researchers has demonstrated that the brains ability to comprehend and form memories of speech may be significantly reduced as we drift off to sleep. According to the study, researchers monitored the participants’ response to speech when they were awake/alert, sedated and deeply sedated. The results suggested that during the alert phase participants actively perceived and encoded the speech sounds to memory, during the lightly sedated period, participants were only able to perceive sound but could not encode them to memory. In the deepest level of sedation participants were not able to do neither.
The results suggest differences in the brains ability to respond and process speech during reducing levels of awareness.
PNAS Oct. 9 2007 vol. 104 (41): 16032-16037