Humans do it, and so do dogs and birds and some other animals. And a new study shows that spiders just might dream, too.⁠ ⁠ For the study, published Monday in the journal Proceedings of the National Academy of Sciences, researchers examined infrared videos of dozens of young jumping spiders sleeping at night. The tiny spiders, which capture their prey using their acute vision and jumping prowess, sleep upside down hanging by a strand of silk.⁠ ⁠ The videos showed that the spiders periodically twitched and curled their legs as their so-called retinal tubules—components of their lidless eyes—shifted rapidly to indicate that they were experiencing rapid-eye-movement, or REM, sleep. The periods of REM sleep came every 15 to 20 minutes, with each period lasting about 90 seconds. ⁠ ⁠ “When I saw for the first time these twitching faces, it just blew my mind because it looked like when cats or dogs dream,” said Daniela C. Roessler, a postdoctoral fellow at Germany’s University of Konstanz and the study’s lead author. ⁠ ⁠ The finding is a game changer in scientists’ understanding of sleep in different animals, said Paul Shaw, a professor of neuroscience at Washington University School of Medicine in St. Louis who wasn’t involved in the new research.⁠ ⁠ “If spiders have REM sleep, then it changes the landscape of when REM evolved,” Dr. Shaw said, adding that the finding “expands the number and types of animals that exhibit this human state.”⁠ ⁠ Read more at the link in our bio.⁠ ⁠ Video: Daniela C. Roessler