Maybe we should learn from Northern elephant seals to nap.
Northern elephant seals, whose scientific name is Mirounga angustirostris, swim for months with short breaks. During these lengthy swims, they nap for only about 20 minutes. Throughout one day, they only have two hours of sleep!
Jessica Kendeall-Bar, who studies aquatic animals at the University of California in San Diego, said, “It’s important to map these extremes of [sleep behavior] across the animal kingdom.” Kendall-Bar started a study to see how and if Northern elephant seals sleep, and it was successful.
First, they dived 60-100 meters under the water. As the seal begins to fall asleep, they hold themselves upright for a few more minutes before they go into REM sleep.
The Northern elephant seals spend almost all year in the Pacific Ocean, where they hunt for squids and fish. The seals get hunted by sharks and killer whales. Since they are more exposed at the surface of the water, they only go up for air each 10-30 minutes.
“People had known that these seals dive almost all the time when they’re out in the ocean. But it wasn’t known if and how they sleep ,” said Niels Rattenborg. He wasn’t in the study of the seals, but Rattenborg works at Max Planck Institute for Biological Intelligence in Seewiesen, Germany.
Kendall-Bar’s team of researchers put special caps on two of seals to see how the seals slept. These caps could note down the animals’ brain waves, which could tell the team when the seals were asleep. The team also put motion sensors on the animal.
Kendall-Bar’s team then took the seals from Año Nuevo State Park to a shore about 37 miles away. To swim back to their original beach, the seals had to cross the Monterey Canyon, where the waters are similar to the Pacific Ocean. When they swam back to their home, they had to sleep, and since they have caps and motion sensors on them, the team would know when and how the seals are sleeping.
When the seals started their trek back to their home, the researchers got the answer to how Northern elephant seals slept. First, diving down 60-100 meters. Then holding themselves upright for a few seconds before they fell asleep.
A sleeping seal now floats upside down as it drifts downward. During one of these “falling naps,” a seal can descend for more than 100 meters.
Sharks and killer whales don’t go that deep into the water, so the seals are safe from predators.
After 5-10 minutes, the elephant seal wakes up and swims back to the surface. The whole process takes only about 20 minutes, which is how long an average human being takes to fall asleep.
However, even though the seals only get about two hours sleep per day, when they go on land to mate and molt, they sleep for nearly half the day.
“What the seals are doing [at the beach] might be something like what we do when we sleep in on the weekend,” Rattenborg said.
Weirdly enough, elephant seals are different from other marine animals. While they only sleep with one half of a brain “turned off” to watch out for predators, the elephant seals sleep with both brains turned off.
“It’s pretty cool that elephant seals get by without one-sided sleep,” Kendall-Bar said. “They’re shutting off both halves of their brain completely and leaving themselves vulnerable.”
However cool or weird, though, we could all agree that Northern elephant seals are the masters of napping.
Northern elephant seals, whose scientific name is Mirounga angustirostris, swim for months with short breaks. During these lengthy swims, they nap for only about 20 minutes. Throughout one day, they only have two hours of sleep!
Jessica Kendeall-Bar, who studies aquatic animals at the University of California in San Diego, said, “It’s important to map these extremes of [sleep behavior] across the animal kingdom.” Kendall-Bar started a study to see how and if Northern elephant seals sleep, and it was successful.
First, they dived 60-100 meters under the water. As the seal begins to fall asleep, they hold themselves upright for a few more minutes before they go into REM sleep.
The Northern elephant seals spend almost all year in the Pacific Ocean, where they hunt for squids and fish. The seals get hunted by sharks and killer whales. Since they are more exposed at the surface of the water, they only go up for air each 10-30 minutes.
“People had known that these seals dive almost all the time when they’re out in the ocean. But it wasn’t known if and how they sleep ,” said Niels Rattenborg. He wasn’t in the study of the seals, but Rattenborg works at Max Planck Institute for Biological Intelligence in Seewiesen, Germany.
Kendall-Bar’s team of researchers put special caps on two of seals to see how the seals slept. These caps could note down the animals’ brain waves, which could tell the team when the seals were asleep. The team also put motion sensors on the animal.
Kendall-Bar’s team then took the seals from Año Nuevo State Park to a shore about 37 miles away. To swim back to their original beach, the seals had to cross the Monterey Canyon, where the waters are similar to the Pacific Ocean. When they swam back to their home, they had to sleep, and since they have caps and motion sensors on them, the team would know when and how the seals are sleeping.
When the seals started their trek back to their home, the researchers got the answer to how Northern elephant seals slept. First, diving down 60-100 meters. Then holding themselves upright for a few seconds before they fell asleep.
A sleeping seal now floats upside down as it drifts downward. During one of these “falling naps,” a seal can descend for more than 100 meters.
Sharks and killer whales don’t go that deep into the water, so the seals are safe from predators.
After 5-10 minutes, the elephant seal wakes up and swims back to the surface. The whole process takes only about 20 minutes, which is how long an average human being takes to fall asleep.
However, even though the seals only get about two hours sleep per day, when they go on land to mate and molt, they sleep for nearly half the day.
“What the seals are doing [at the beach] might be something like what we do when we sleep in on the weekend,” Rattenborg said.
Weirdly enough, elephant seals are different from other marine animals. While they only sleep with one half of a brain “turned off” to watch out for predators, the elephant seals sleep with both brains turned off.
“It’s pretty cool that elephant seals get by without one-sided sleep,” Kendall-Bar said. “They’re shutting off both halves of their brain completely and leaving themselves vulnerable.”
However cool or weird, though, we could all agree that Northern elephant seals are the masters of napping.
