University of Bonn researchers discover REM-like sleep in spiders

Researchers from the University of Bonn have provided the first experimental evidence that spiders experience regulated sleep stages, including a phase similar to Rapid Eye Movement (REM) sleep found in humans and other vertebrates.

The study, published in the journal PNAS, focused on the Australian jumping spider, Portia fimbriata. Using high-resolution infrared cameras, scientists observed the spiders undergoing distinct sleep architectures. During the REM-like phase, the spiders exhibited rapid eye movements and involuntary muscle spasms in their legs and silk-producing organs.

To confirm the subjects were actually sleeping rather than merely remaining inactive, the team used acoustic stimuli. They found that during these active sleep episodes, the spiders showed significantly delayed reactions to loud noises. The findings suggest that complex sleep patterns may be more widespread across different nervous systems than previously understood, potentially offering new insights into the evolution of sleep.