Overview
- Researchers recorded the Australian jumping spider Portia fimbriata and published behavioral evidence in PNAS on Oct. 26, 2026 that the animal cycles between a quiescent rest and a REM-like sleep marked by eye movements and limb and mouthpart twitches.
- The team confirmed the animals were truly asleep by using high-resolution infrared video, measuring slowed reaction times to sound stimuli, and showing a characteristic night-time resting posture.
- When investigators disrupted night-time rest by introducing live fruit flies, spiders showed an about 80% increase in REM-like behavior the next night, demonstrating REM rebound and homeostatic sleep regulation.
- The findings rely on detailed behavior rather than brain recordings, so links to memory consolidation or dreaming remain untested and require neural recordings and causal experiments.
- Authors plan field studies in northern Australia, broad comparative surveys across spider species, and neurophysiological work to assess ecological impacts such as artificial light at night and to probe sleep’s cognitive functions.