There are many unresolved scientific questions that keep experts and others up at night. One of them… if the spiders are sleeping.

Trying to find an answer, Daniela Resler and her team set up cameras to watch the baby spiders at night.

As it turned out, their behavior showed signs reminiscent of sleep cycles: their legs shook, and part of their eyes opened and closed.

Researchers believe that the above resembles the state of REM sleep. In humans, REM (rapid eye movement) sleep is when parts of the brain are active and closely associated with dreams.

Other animals, such as some birds and mammals, appear to experience REM sleep. But creatures like spiders haven’t been studied enough to see if they sleep in this way, according to Resler, an evolutionary biologist at the University of Konstanz in Germany.

Resler and her colleagues studied jumping spiders, a fairly common species with a hairy brown body and four pairs of eyes. They noticed that at night they hang on spider webs.

“It was the strangest thing I have ever seen,” says the scientist.

He says the study has shown that the spiders’ movements at night are reminiscent of other species’ REM sleep, such as when dogs or cats shake in their sleep. And in fact, these movements occur in regular cycles, just like human sleep cycles.

Of course, many spider species don’t have moving eyes, so it’s hard to compare how they sleep.

But jumping spiders are predators that move their retinas while hunting. In addition, young spiders have a transparent outer layer, so their bodies are clearly visible.

Researchers have not determined whether spiders actually sleep in this dormant state. Other tests will need to be done, for example, for researchers to see if the spiders are moving slowly or moving towards external factors at all.

On the other hand, creatures like spiders are far from human in the way they evolve. Another sleep researcher, Jerry Siegel, has expressed doubt that spiders actually sleep.

“There are many animals that show some activity when they are at rest. But is it REM sleep? It’s hard to imagine that they are the same,” says a researcher at the UCLA Sleep Research Center.

On the other hand, Barrett Klein, an entomologist at the University of Wisconsin-La Crosse, said the results of the study are very interesting. As he mentions, there are many questions about how widespread REM sleep is and what its benefits are.

“REM sleep is a clean slate,” he says.

According to the Associated Press