Jumping Spider Portia fimbriata Shows REM-Like Sleep, University of Bonn Study Finds

Researchers at the University of Bonn have discovered that the Australian jumping spider Portia fimbriata experiences two distinct sleep stages, including a REM-like state with rapid eye movements and muscle twitches. The findings, published in the Proceedings of the National Academy of Sciences, suggest that complex sleep patterns may be more widespread in the animal kingdom than previously thought. While humans and other vertebrates are known to cycle through sleep stages, observing similar behavior in an invertebrate challenges assumptions about the evolution of sleep. The study focused on the spider's nocturnal resting periods, during which researchers noted periodic bouts of retinal movement and limb jerking reminiscent of REM sleep. This discovery could open new avenues for understanding the purpose of dreaming and the fundamental biology of sleep across species. The work highlights Portia fimbriata as a valuable model for studying sleep in simple nervous systems, potentially shedding light on why REM sleep evolved and its role in memory and learning.