Study finds regulated sleep and REM-like episodes in Portia fimbriata jumping spiders

Experiments on Portia fimbriata found a daily activity rhythm, reduced responsiveness during REM-like bouts and extra rest after nighttime disruption, supporting the researchers’ conclusion that the spiders undergo regulated behavioral sleep. Earlier work observed REM-like movements in another jumping spider species. The new study relies on behavior, not measurements of brain activity, and the movements do not show that spiders dream.