SCIENCE
WE’RE INTIMATELY FAMILIAR with what a sleeping human looks like, or a sleeping dog or bird. But what does a sleeping ant look like—or a sleeping jellyfish? Despite spending a third of our lives asleep, we still haven’t cracked all its secrets, but becoming more adept at recognizing the state in other species could explain why sleep is so important to us.
Sleep—or at least some activity that looks an awful lot like it—is pretty common for all living creatures: among not just humans and our close relatives but also birds, reptiles, fish, insects and even a microscopic worm, called Caenorhabditis elegans, found in many science labs.