Jumping spiders – Salticidae – show rapid eye movements and limb twitches similar to what is observed in dogs and cats in sleep, researchers say, reports The Guardian.

The question is not “do you have nightmares about spiders” but do you have nightmares about spiders? About juicy flies, about people?

Research by the European-American partnership suggests that thousands of species of jumping spiders can experience rapid eye movement, the stage of sleep during which the most intense dreams occur. Although the research in question does not conclude that spiders dream.

A team from universities in Germany, Italy and Harvard University in the US observed the arachnids during nocturnal inactivity using infrared cameras and found “periodic bouts of retinal movements accompanied by limb twitches and stereotypical leg twitches”.

While the researchers don’t say the spiders definitely experienced anything similar to human sleep, they say they’re left with “a deeper question about whether jumping spiders can experience visual dreams.”

“They had uncontrollable spasms that were very similar to when dogs or cats dream and have their little REM phases,” Daniela Ressler, a biologist at the University of Konstanz in Germany and lead author of the study, told Scientific American.

“Whether that means they have a visual experience similar to the way we experience visual dreams is a different story,” she told the Washington Post in a separate interview.

She suggested that spiders can dream “because of vibrations”.

The team’s findings were published this month in the Proceedings of the National Academy of Sciences (PNAS).

Resler said the study of REM sleep still focuses on terrestrial vertebrates, particularly mammals and birds, while studies on insects and arachnids are rare.