# Jumping spider Portia fimbriata shows REM-like sleep with raised arousal threshold and sleep rebound

- Published: 2026-11-14 20:41 UTC
- Section: Life & Health › Biology & biochemistry
- Tags: spider sleep, REM-like sleep in spiders, Portia fimbriata, jumping spiders Salticidae, free-running circadian rhythm, arousal threshold, sleep rebound, sleep in invertebrates, evolution of sleep, University of Bonn
- URL: https://realtech.media/news/rt-4e7f15e64381fbd6d5e67ab3_jumping_spider_portia/

**Behavioral experiments on the jumping spider Portia fimbriata show sleep with a REM-like substate, raised arousal threshold and rebound after disruption, the authors report.**

![Jumping spider Portia fimbriata shows REM-like sleep with raised arousal threshold and sleep rebound](https://realtech.media/media/2026/11/01dec4035c5cc7c2.jpg)
*Techno-Science*

Biologists from the University of Bonn studied sleep in the jumping spider Portia fimbriata (family Salticidae), a small Australian species that hunts other spiders. The results appear in Proceedings of the National Academy of Sciences. The authors conclude that the behavior they observed is behavioral sleep and that it includes an REM-like substate in a terrestrial invertebrate [1].

Sleep research is strongly biased toward vertebrates, and studies are scarce or absent in most invertebrate lineages. An earlier report of REM-like behavior in a jumping spider described unexpected parallels to sleep in vertebrates. Experimental evidence that such behavioral indicators truly represent sleep in spiders was still lacking [1].

## Activity rhythm and sleep structure

The researchers filmed the spiders' nights. They describe diurnal activity and a free-running circadian rhythm, meaning a cycle that persists without external time cues [1]. The sleep architecture proved robust, with two clearly different periods. In one the spider stays almost motionless, in the other its legs twitch and its eyes move rapidly, which resembles the REM phase of human sleep. The REM-like behaviors occurred regularly [1].

## Arousal threshold and rebound

Immobility alone does not prove sleep, so the team tested how the spiders respond to stimuli. They played small sounds and observed the reaction. Arousal thresholds were elevated during the REM-like states [1].

In a second experiment the authors prevented some spiders from sleeping normally. After the disruption the animals showed rebound effects: they spent more time asleep, as if recovering lost sleep [1]. Together with the other measurements, this is the basis for the authors' conclusion that the behavior is sleep rather than simple quiet.

## What the data do not show

The study does not show that spiders dream. The leg and eye movements resemble those seen in human REM sleep, but what a spider experiences in this phase is unknown, and brain activity was not measured.

The authors say the results contribute to fundamental questions about the evolution and function of sleep across animals. Studying more species could show whether such phases of rest appeared early in animal evolution.

## Sources

1. [Proceedings of the National Academy of Sciences](https://doi.org/10.1073/pnas.2618030123)
2. [Techno-Science](https://www.techno-science.net/fr/actualites/araignees-sommeil-revent-sommeil-paradoxal-29676)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-4e7f15e64381fbd6d5e67ab3_jumping_spider_portia/