D-state

The term "D-state" refers to desynchronized or dreaming sleep, characterized by rapid eye movements and brain wave patterns similar to an alert waking state. This stage of sleep, also known as REM sleep, is associated with vivid dreaming and increased brain activity. D-state sleep has been observed in various mammals, birds, and reptiles.1

Physiological research in 1953 discovered the link between REM sleep and dreaming. When subjects were awakened during REM sleep, they reported vivid dreams significantly more often than when awakened during non-REM sleep. This stage involves specific brain stem structures and neurochemicals like norepinephrine. While dreaming is primarily linked to REM sleep, some dream-like experiences can occur during non-REM sleep, often described as more thought-like. Chronic deprivation of D-state sleep leads to a "rebound effect" where individuals dream more on subsequent recovery nights.1