No matter how many cute pet videos I watch in my life, I will always have a soft spot for this work of art entitled "sleeping dog runs into wall."
Wonderful sleep-running dog. Video: jaa71954/YouTube
This adorably somnambulant dog appears to be deep in the throes of REM sleep, and isn't quite able to shake its dreams off in time to adjust for the reality of Newton's second law of motion.
Not only does this home movie seem oddly relatable—haven't we all experienced such rude awakenings in our lives?—it also raises the question of how animals experience sleep, and what that might reveal about the evolutionary role of slumber in the wider natural world. This line of reasoning, in turn, can shed light on the mechanisms governing human sleep—and potentially, how to manipulate them.
With that in mind, here are our picks for the five oddest sleep behaviors found on Earth, from using one's own butt as a pillow, to resting up before a big moult.
THE DREAMS OF DUCK-BILLED PLATYPUSES
Everything that platypuses choose to be is weird, and their sleeping habits are no exception. As The New York Times put it, 'the somnolent mind of the platypus is no joking matter." These egg-laying aquatic creatures sleep about 14 hours a day, and about half of that time is spent in REM sleep.
That's more REM time than any other mammal or bird, and when coupled with the fact that platypuses have been observed mimicking their waking motions while asleep, it suggests these weirdos may well be active dreamers. This is especially important because platypuses are an evolutionary throwback to the dawn of mammals, so understanding how they sleep is relevant to finding out the evolution of sleep in mammals, reptiles, and perhaps even dinosaurs.
Much like platypuses, giraffes are total oddballs that look like they've been built from spare parts sourced from other species. But when it comes to sleep patterns, the two animals couldn't be more different. While platypuses slumber away over half their life, giraffes are some of the most committed insomniacs in nature, taking short power naps that only add up to about 30 minutes of shuteye over 24 hours, according to the Sleep Foundation. As such, they have the most minimal sleep requirements of any mammal.
What's more, giraffes catch these brief moments of slumber in crazy pretzel-like positions. Because they are such a jumble of elongated body parts, they have to curl their necks in arching loops in order to use their own butts as pillows. Voila:
Giraffe sleeping compilation. Video: New Crash Compilations Daily/YouTube
HONEYBEES LIKE US
Mammals aren't the only group of animals that need to catch up on some z's every once in awhile. Many insects also require bouts of sustained rest, or torpidity, in order to retain their full health and vitality, including honeybees. These crucial pollinators are known to take several brief naps throughout the day, as well as dormancy during nocturnal hours. (Fun fact: you can tell that that a honeybee is sleeping if its antennae are drooping, which is objectively adorable.)
Moreover, missing out on a good night's sleep seems to mess with bee brains as much as it disrupts human cognitive performance. A few years back, researchers at the University of Texas created a honeybee sleep deprivation chamber, which they ingeniously dubbed "the insominator." As it turned out, bees subjected to a rough night in the ole insominator were noticeably less capable of carrying out their duties the next morning, compared to the bees that had been allowed to rest up.
What's interesting here is that honeybees, which are so anatomically different from humans, can have such a similar relationship to sleep, right down to needing roughly eight hours a night.
The fact that honeybees and other insects are known to doze off brings up a salient question—what is the simplest organism that has ever been observed indulging in something resembling naptime?
That honor goes to the model organism Caenorhabditis elegans, a nematode worm that has become an entrenched workhorse in laboratories around the world—in fact, six scientists owe their Nobel Prizes to these tiny creatures. Among the many insights that have resulted from C. elegans research is confirmation that even basic lifeforms slip into sleep-like states known as "lethargus."
Typically, these nematodes sleep for about 2.6 hours, with the lethargus often preceding the moulting of the worms' shell-like cuticles. According to a 2008 paper in Nature, this timing suggests that "sleep may have evolved to allow for developmental changes." Moreover, C. elegans appears to get all the reparative benefits of snoozing observed in animals of greater complexity, including humans.
BOTTLENOSE DOLPHINS SEE YOU WHEN THEY SLEEP
"Sleep with one eye open" has become a catchphrase in Western movies and Metallica songs, but it's also standard operating procedure for dolphins, as well as many other marine mammals.
In a phenomenon known as unihemispheric slow wave sleep (USWS), these wary snoozers switch off one side of their brain while keeping the other alert against predators, and vigilant against the threat of literally drowning with drowsiness. Dolphins and their kin can shift back and forth between these two hemispheres, like some neurological version of sentries changing guard.
In addition to marine mammals, several bird species use USWS to keep tabs on their environment while simultaneously drifting off into dreamland. Some of them may even be able to fly long distances in their sleep. The common swift, for example, is almost permanently airborne, and can fly for at least 200 days without touching down on land. Much like dolphins, these flyers have found a way to catch some shuteye on the road—one brain hemisphere at a time.
You'll Sleep When You're Dead is Motherboard's exploration of the future of sleep. Read more stories.