We tested the new threat simulation theory of the biological function of dreaming by analysing 592 dreams from 52 subjects with a rating scale developed for quantifying threatening events in dreams. The main predictions were that dreams contain more frequent and more severe threats than waking life does; that dream threats are realistic; and that they primarily threaten the Dream Self who tends to behave in a relevant defensive manner in response to them. These predictions were confirmed and the theory empirically supported. We suggest that the threat simulation theory of dreaming may have wider implications for theories about the function of consciousness. Copyright © Antti Revonsuo & Katja Valli 2000.