Autonoetic (self-knowing) consciousness is distinguished from noetic (fact-knowing) dreaming within the Multistate Hierarchical Model of Consciousness. The two develop in tandem in children aged 5–7 and 9–11, revealing both similarities and differences. Lucid dreaming—awareness of dreaming while dreaming—is explained as a small atypical expansion of the neurocognitive network supporting dreaming. Because that network lacks the capabilities of the consciousness network, three unexpected findings from quantitative dream studies are explained: the rare inclusion of episodic memories in dreams, the apparent absence of figurative thinking and symbolism, and the relative infrequency of emotions compared to waking thought and traditional beliefs.
The adaptive inactivity theory of sleep explains several unusual features of human sleep. Indigenous groups without electricity sleep on average only 5–7 hours a night and sleep longer in the winter than in the summer by almost an hour. Unlike other primates, the human sleep cycle is linked to the temperature cycle, not the light–dark cycle. Laboratory studies of cerebral blood flow during sleep are consistent with activation patterns during the sleep-onset process, REM sleep, and early morning NREM 2 sleep. Dream reports after NREM 2 awakenings become increasingly frequent and similar in content to REM dreams by morning. Dreaming occurs when the imagination network is active and other neurocognitive networks are not.