Evolutionary function of dreams: A test of the threat simulation theory in recurrent dreams

Revonsuo (2000a) proposed an intriguing and detailed evolutionary theory of dreams which stipulates that the biological function of dreaming is to simulate threatening events and to rehearse threat avoidance behaviors. The goal of the present study was to test this theory using a sample of 212 recurrent dreams that was scored using a slightly expanded version of the DreamThreat rating scale. Six of the eight hypotheses tested were supported. Among the positive findings, 66% of the recurrent dream reports contained one or more threats, the threats tended to be dangerous and aimed at the dreamer, and when facing a threat, the dreamer tended to take defensive or evasive actions that were possible and reasonable. However, less than 15% of the recurrent dreams depicted realistic and probable situations critical for one’s physical survival or reproductive success and the dreamer rarely succeeded in fleeing the threat despite important and appropriate efforts. The findings thus provide mixed support for the threat simulation theory.