ABSTRACT
Sleep is phenomenologically rich, supporting diverse kinds of conscious experience as well as transient loss of consciousness. Sleep is also cognitively and behaviorally rich, with different sleep stages supporting different kinds of memory processing as well as sleep behaviors ranging from subtle muscle twitches to seemingly goal-directed behaviors, as in sleepwalking, sleep talking, and rapid eye movement-sleep behavior disorder. Dreaming is notoriously heterogeneous, with different kinds of dreams having distinct phenomenological profiles. For example, lucid dreams, in which dreamers become aware that they are dreaming, often additionally involve the ability to control the ongoing dream. There is also variation in dreams from different participant groups. Dreams contain an average of 2–4 dream characters only one of these, at a given time, is experienced as the self. Self-other distinctions therefore play a central role in dreams: world simulation—both in a spatial and in a social sense—is necessarily grounded in the experience of a single self at its center.
