Animals have evolved to sleep in extreme ways — for example, taking micro naps during parenting, sleeping on the wing during ...

Some animals can sleep with just half their brain at a time. Understanding this phenomenon can help us learn more about human ...

The hydra is a simple creature. Less than half an inch long, its tubular body has a foot at one end and a mouth at the other. The foot clings to a surface underwater—a plant or a rock, perhaps—and the ...

Every animal with a brain needs sleep — and even a few without a brain do, too. Humans sleep, birds sleep, whales sleep and even jellyfish sleep. Sleep is universal “even though it’s actually very ...

For humans, sleep is a necessity, a mystery, and a luxury. It’s not known why we need it but we do—and an hour more or less of it can make your day either great or grumpy. Most animals sleep, too, ...