Chinstrap penguins may be contenders for the title of “world’s greatest power nappers.” A recent study found that penguins that are watching over their eggs or chicks nod off more than 10,000 times a day—for an average of just four seconds per nap.

Chinstrap penguins live in Antarctica and nearby islands. Adults stand about two and a half feet tall, and weigh up to 10 or 12 pounds. They get their name from a thin line of black feathers that look like a chinstrap. They return to their nesting grounds every October or November—hundreds of thousands or more in a single colony.

Males and females take turns watching over the nests while the other spend days fishing. Other chinstraps may try to steal the pebbles from their nests. And birds known as brown skuas try to grab the eggs or chicks. So nest-sitting is a full-time chore.

Researchers studied 14 adults on King George Island, off the coast of Antarctica. They used sensors to record the penguins’ brain activity. They also logged location, motion, and other data.

The instruments revealed that nesting parents frequently nodded off, then quickly popped back awake. The brain monitors showed that the parents were catching frequent naps—sometimes with only one side of the brain, sometimes the whole thing. The naps added up to 11 hours a day.

That behavior wouldn’t be healthy for most animals. But it didn’t seem to bother the chinstrap penguins. Instead, it helped them protect their budding young families.