Spiders Don’t Just Sit Still At Night: Scientists Show They Fall Into Genuine, Regulated Sleep

At night, the Australian jumping spider Portia fimbriata hangs upside down beneath a thread of its own silk and goes almost completely still. For a long time, it would have been reasonable to assume the little hunter was simply resting; however, a new study from the University of Bonn suggests something much more interesting is going on: the spider appears to sleep in two separate stages, and one of them looks a lot like the REM sleep humans drift into every night.