Receive emails about upcoming NOVA programs and related content, as well as featured reporting about current events through a science lens. Email Address Zip Code Subscribe

For the great frigatebird, a good night’s sleep might be just 41 minutes long.

Scientists at the Max Planck Institute for Ornithology in Germany have

Support Provided By Learn More

confirmed that the large seabird can sleep while simultaneously flying through the air, allowing them to travel vast distances non-stop, sometimes for months at a time.

They found that the birds slept for only brief periods—about 12 seconds at a time—while in flight, and usually with only half of their brain. Over the course of 24 hours, they might squeeze in 40 minutes or so in these short bursts. (When they do reach land, though, they zonk out for 12 hours at a time.

The frigatebird migrates by flying up to two months continuously while resting mid-flight.

To solve this riddle, the scientists fitted small brain activity monitors and movement trackers to 14 great frigatebirds.

Here’s Alice Klein reporting with New Scientist :

Frigatebirds in flight tend to use one hemisphere at a time to sleep, as do ducks and dolphins, but sometimes they used both. “Some people thought that all their sleep would have to be unihemispheric otherwise they would drop from the sky,” said Niels Rattenborg, the lead author of the study. “But that’s not the case – they can sleep with both hemispheres and they just continue soaring.”

The birds’ were able to stay aloft during these brief naps thanks to the extra lift provided by rising air currents, allowing the birds to glide as they doze off. For frigatebirds, this capability may have evolved because they lack the waterproof feathers necessary to float and swim—and sleep—on the ocean.

The fact that this mid-flight sleep has evolved at all shows just how important sleep must be for the development of all animals. If scientists figure out how birds can successfully function on so little sleep, it could shed light on how sleep loss functions in humans.