Memory reactivations during sleep: a neural basis of dream experiences?

Newly encoded memory traces are spontaneously reactivated during sleep. Since their discovery in the 1990s, these memory reactivations have been discussed as a potential neural basis for dream experiences. New results from animal and human research, as well as the rapidly growing field of sleep and dream engineering, provide essential insights into this question, revealing both strong parallels and disparities between the two phenomena. We suggest that while memory reactivations may contribute to subjective experiences across different states of consciousness, they are not likely to be experienced directly as dreams. We identify important limitations in current research paradigms and suggest novel strategies to address this question empirically.