The origins of consciousness may lie not in the cerebral cortex but in ancient subcortical systems responsible for affective experience, particularly the ascending arousal networks of the upper brainstem and the periaqueductal gray. These structures sustain wakefulness and imbue it with valence, positioning consciousness as an embodied biological function grounded in feeling rather than higher cognition. From a developmental perspective, these subcortical structures mature relatively early in gestation, suggesting that a primitive form of subjective feeling may emerge during the third trimester, before cortical maturation. This view has ethical implications for debates on fetal pain perception, neonatal care, and treatment of individuals with profound cognitive impairment.
Events and memories from waking life can reappear in dreams, either literally or indirectly. Two temporal patterns are known: the day-residue effect (features from the previous day) and the dream-lag effect (features from 5–7 days earlier). Previous work used spontaneous home dream reports from both REM and NREM sleep. This study tested whether the dream-lag effect occurs only in REM or also in NREM stage 2 (N2) dreams. Twenty participants kept daily diaries for over a week, then slept in a laboratory for two nights. REM and N2 dreams were collected, and participants rated correspondence between each dream and diary entry. The dream-lag effect appeared for REM but not N2 dreams, even after accounting for dream length.