Cameras were pointed at young jumping spiders at night by Daniela Roessler and her colleagues to investigate. The spiders’ legs twitched, and some of their eyes flickered in the video, which revealed patterns that closely resembled sleep cycles.
A “REM sleep-like state,” as the researchers put it, could be seen in this pattern. Rapid eye movement, also known as REM in people, is a sleep stage that is active and strongly associated with dreaming. During this stage, certain areas of the brain become active.
It has been demonstrated that some birds and mammals, as well as other animals, can experience REM sleep.
According to Roessler, an evolutionary biologist at the University of Konstanz in Germany, animals like the jumping spider haven’t received as much attention, so it wasn’t known if they got the same kind of sleep.
Following her discovery of the spiders hanging at night in their lab containers on silk threads, Roessler and her team investigated the sleep issue. Jumping spiders are a common species with a brown furry body and four sets of large eyes, and she had just collected some of them to study.
According to the study, the spiders’ nocturnal movements resembled REM in other species, such as the twitching of sleeping dogs or cats. And they occurred in predictable cycles, much like how people sleep.
As per study co-author and evolutionary biologist Paul Shamble of Harvard University, many species that resemble spiders actually lack movable eyes, making it challenging to compare their sleep cycles.
However, these jumping spiders are predators that move their retinas to alter their gaze while hunting, according to Shamble. The young spiders also have a transparent outer layer that allows a clear view of their bodies.
According to Roessler, while the spiders are in these resting states, the researchers still need to determine if they are technically sleeping. This includes determining whether they react to triggers that would typically set them off more slowly or not at all.