Overview
- A peer-reviewed paper published on Oct. 26, 2026 in Proceedings of the National Academy of Sciences reports that the jumping spider Portia fimbriata cycles between two distinct sleep stages, including a REM-like phase.
- Researchers filmed spiders with infrared cameras and tested responsiveness, finding REM-like bouts that averaged about 83 seconds and much slower reaction times compared with wakefulness.
- When scientists disturbed sleep by introducing buzzing fruit flies, spiders lengthened sleep windows and roughly doubled total REM-like time from about nine minutes to about seventeen minutes, showing a compensatory rebound.
- The results are behavioral only: the study measured posture, twitching, eye movements and response delays but did not record spider brain activity, so claims about dreaming remain unproven.
- Authors say the finding widens questions about the evolution and function of structured sleep and they plan field comparisons, broader species sampling, and neural follow-ups to test causes and ecological effects such as artificial light.