Animals likely experience dreams, though the content and nature of those dreams remain uncertain. This review evaluates evidence from neural activity monitoring, memory replay, and dream-like behaviors, focusing on sleep patterns such as REM, slow-wave, and unihemispheric sleep that are linked to dreaming. It proposes studying octopuses as a novel way to decipher animal dream content and also examines atypical sleep patterns and deviations from ordinary dreaming.
Humans cycle through NREM and REM sleep, with dreaming occurring in both stages but more frequently during REM. Whether non-human animals experience the same sleep cycles and therefore dream remains uncertain. By reviewing research on sleep behaviors and experiments in mammals, reptiles, and cephalopods, the author examines evidence for REM/NREM sleep and dreaming in animals. Establishing whether animals dream could help neuroscientists better understand human dreaming, its purpose, and the meaning of dream content.