Additional Coverage:
- The secret world of animal sleep (apnews.com)
The Wild World of Extreme Sleep: How Animals Catch Zs in Unconventional Ways
Even in the animal kingdom, everyone needs their beauty rest. From humans to whales, and even jellyfish (yes, jellyfish!), sleep is a universal necessity.
But for some creatures, catching a few winks isn’t as simple as snuggling under a blanket. In fact, for many, sleep can be downright dangerous.
“Sleep is universal even though it’s actually very risky,” explains Paul-Antoine Libourel, a researcher at the Neuroscience Research Center of Lyon in France. When an animal nods off, it becomes vulnerable to predators. Yet, the drive to sleep is so powerful that no creature can entirely forgo it, no matter how inconvenient.
This fundamental need has led to some truly remarkable evolutionary adaptations, giving rise to what scientists are calling “extreme sleep.” Animals living in challenging environments have developed ingenious ways to grab shut-eye, whether it’s stealing seconds during constant parenting, dozing mid-flight during epic migrations, or even napping while swimming.
For years, scientists could only guess at wild animals’ sleep habits, observing when they appeared still or closed their eyes. But thanks to miniature trackers and brainwave-measuring helmets-think tiny versions of human sleep lab equipment-researchers are now getting unprecedented glimpses into the spectacular and varied ways wild animals snooze.
“We’re finding that sleep is really flexible in response to ecological demands,” notes Niels Rattenborg, an animal sleep research specialist at the Max Planck Institute for Biological Intelligence in Germany.
Let’s dive into some of these fascinating examples:
Chinstrap Penguins: The Masters of the Microsleep
Imagine being a chinstrap penguin parent in Antarctica. You and your mate share the grueling task of incubating an egg or guarding a fluffy chick while the other fishes for food.
This nonstop routine can last for weeks. How do they manage to get any sleep?
Their secret: thousands of “microsleeps” a day, each lasting a mere four seconds. Biologist Won Young Lee from the Korea Polar Research Institute explains these brief power naps are enough for the penguins to keep their caregiving duties going in their bustling, noisy colonies.
Researchers, measuring brain activity in 14 adult penguins over 11 days, found that these tiny naps cumulatively add up to about 11 hours of sleep per day. When a clumsy neighbor or a predatory seabird approaches, the penguin blinks, stays alert, then quickly dozes off again, its chin nodding like a sleepy driver.
This ability to function on extremely fragmented sleep is a unique adaptation for their demanding breeding season. Scientists can even observe when one or both hemispheres of their brains are asleep.
Frigatebirds: Sleeping on the Wing
Poets and sailors have long pondered whether birds that fly for months without touching down ever actually sleep. The answer, for some, is a resounding yes! Scientists discovered this by attaching brainwave-measuring devices to great frigatebirds in the Galapagos Islands.
These magnificent seabirds can sleep with one half of their brain at a time while in flight. The other half remains semi-alert, allowing one eye to stay open and watch for obstacles. This incredible adaptation enables them to soar for weeks without landing, crucial for their delicate, non-water repellent feathers.
While they can’t perform complex maneuvers like flapping or diving with only half a brain awake, frigatebirds have evolved to sleep while gliding and circling on warm air currents, minimizing effort. When they return to their nests, their sleep patterns shift, with longer bouts of whole-brain sleep, suggesting their in-flight napping is a specialized adaptation for sustained flight. Dolphins and some other birds, like swifts and albatrosses, also exhibit similar sleeping hacks.
Frigatebirds can cover an astonishing 255 miles a day for over 40 days straight, a feat made possible only by their ability to sleep while airborne.
Elephant Seals: Deep-Sea Slumber
For a 5,000-pound northern elephant seal, life on land is a breeze. But at sea, sleep is a perilous affair, with sharks and killer whales always lurking. These seals embark on epic foraging trips, lasting up to eight months, diving hundreds of feet to hunt for fish and squid.
During these deep dives, which can last around 30 minutes, elephant seals manage to snatch about 10 minutes of sleep, as research led by Jessica Kendall-Bar of Scripps Institution of Oceanography revealed. Her team developed a special neoprene headcap to monitor brain activity and motion during dives, retrieving the data when the seals returned to Northern California beaches.
The 13 female seals studied tended to sleep during the deepest parts of their dives, safely below the typical patrol depths of predators. Their sleep included both slow-wave and REM sleep. During REM sleep, much like humans, the seals experienced temporary paralysis, and their dive motion transformed from a controlled glide to a peculiar “sleep spiral” where they sometimes turned upside down and spun.
At sea, these seals averaged only about two hours of sleep in a 24-hour period (compared to around 10 hours back on the beach!).
Scientists are continually unraveling the mysteries of sleep and just how much we truly need. While humans likely can’t adopt these extreme animal sleep hacks, understanding the incredible flexibility of sleep in the wild showcases nature’s ingenious ability to make shut-eye possible even in the most precarious situations.
Read More About This Story:
- The secret world of animal sleep (apnews.com)