Nodding off is dangerous, so how do some animals sleep?

Frigatebirds snooze in flight while penguins take thousands of 4-second naps a day

- NEW YORK

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 risky,” said Paul-Antoine Libourel, a researcher at the Neuroscience Research Centre of Lyon in France.

Animals that navigate extreme conditions and environments have evolved to sleep in extreme ways. In recent years, tiny trackers and helmets that measure brain waves have allowed researchers to glimpse for the first time the varied and sometimes spectacular ways that wild animals snooze.