"Researchers are finding signs of REM sleep in a broader array of animals than ever before: in spiders, lizards, cuttlefish, zebrafish. The growing tally has some researchers wondering whether dreaming, a state once thought to be limited to human beings, is far more widespread than once thought."

"Marsupial mammals called echidnas show characteristics of REM and non-REM sleep at the same time. Reports on whales and dolphins suggest that they may not experience REM at all. Birds have REM sleep, which comes with twitching bills and wings and a loss of tone in the muscles that hold up their heads."

"Researchers reported a sleep-like state in cuttlefish."

"Researchers have since observed a similar state in octopuses."

"Researchers have also observed a REM-like stage in bearded dragons by recording signals from electrodes in their brains. And they have reported at least two sleep states in zebrafish based on the fishes' brain signatures."

"In pigeons, sleep scientist Gianina Ungurean of the Max Planck Institute for Biological Intelligence in Munich and the University Medicine Göttingen has observed, with colleagues, that pupils constrict during REM as they do during courtship behavior."

"Roundworms appear to have one sleep state only."

A look into the REM dreams of the animal kingdom

#discoveries #biology #sleep #rem #dreaming