By Dr. Becker
Almost everybody knows it’s crucial for health to get the proper amount of sleep. Apparently, animals know it, too, because some of them go to extreme measures to get their zzzs. Those who’ve looked at the science behind sleep may also be aware that REM, or rapid eye movement in a deep sleep that allows us (and animals, too) to dream, is often “characterized by quick, random movements of the eyes,” Medical News Today explains.
Although that’s not always the case, a Nature article contends, because: “As it turns out … the term ‘REM’ is a misnomer: Animals may show REM sleep even though their eyes don’t move, and their bodies don’t twitch.”1
If the first thing you thought of when you read the word “twitch” is how dogs and cats sometimes appear when they’re sleeping, with the slight tremors or involuntary spasms that are so adorable, they’re entering a period of sleep that’s necessary for them to conserve energy, continue doing what they need to do when they’re awake and remain healthy.
Apparently, animals don’t have a circadian rhythm the same way humans do. Noting how some animals sleep is interesting for several reasons, but it’s important for people who sleep with their pets to know the scientific foibles that rest with their pets of choice, which most often seem to be cats and/or dogs: It doesn’t always allow for the deepest sleep, which can become a problem for humans over time.
As Dr. Adrian Morrison, a professor of behavior neuroscience at the University of Pennsylvania School of Veterinary Medicine, notes, “Sleep is composed of two parts: non-REM sleep and REM sleep. To get the full complement of sleep, humans need to have both, but that’s not always the case for animals.”2
What Are Some Sleep Differences Between, Say, an Albatross and a Platypus?
Of course, all animals are different. Mice and anteaters have different patterns, as do fish and caterpillars. Jerome M. Siegel, Ph.D., a professor of psychiatry and biobehavioral sciences at the UCLA Center for Sleep Research, contends that for humans and animals alike, the most important factor regarding sleep is to get the amounts needed to increase their efficiency.3
That can mean vastly different things, depending on the species, as you’ll find when you compare what dreamland looks like for some members of the animal kingdom. Here’s a list of 10 notable differences between animals getting their snooze on:
1. Cat lovers may already be aware their feline friends sleep an inordinate amount of the time — 13 or 14 hours a day or more in most cases. Cats in the wild, like leopards and lions, do most of their sleep during the day. That way they’re better prepared to hunt at night, and they don’t have to be constantly vigilant for self-preservation.
If one or more cats live with you, you may be only too well aware that domestic kitties are quite active at night. In fact, they can be downright frisky, which can be either entertaining or aggravating, depending on where you are in your sleep cycle.
2. Speaking of self-preservation, African Papio baboons sleep “perched” on their heels — arguably at the ready for flight — on tree limbs far above the ground, depending somewhat on their tails for balance rather than holding on, one fascinating study4 noted. Some trees the baboons slept in were singled out solely for that purpose, and were sometimes used by large groups for years.
One particular 45-foot tree researchers focused on touched no other tree, and the trunks of many were covered with thorns, although after long use, thorns on the stout branches were often worn smooth. Several baboons of both sexes and all ages used the same trees, which were often abandoned one or two nights a week as if to confuse potentially marauding lions and leopards.
3. Many people think ants never sleep, but a study on fire ants indicates that these insects living in colonies and having an active social life bust a snooze somewhere around 253 times a day in patterns called “sleep episodes,” each lasting just over a minute.
4. Giraffes, on the other hand, seem to do fine in a state of sleep deprivation, at least from a human perspective: They can go for weeks without taking so much as a catnap and can actually function on as little as five minutes of slumber a day.5
5. Cows and horses can sleep standing up, but they don't experience full REM sleep unless they lie down because their legs have what scientists call the “stay apparatus,” a National Geographic piece reveals:
“Most four-legged land herbivores — cows, moose, rhinos, bison and horses among them — can doze lightly on their feet, but they have to lie down to sleep deeply … Their limbs contain tendons and ligaments that allow the animal to remain standing with minimal muscular effort, and thus allow them to stand — and even doze — for long periods.”6
When horses look as if they’re sleeping standing up, they can either be in a state of drowsiness or what is known as “slow-wave sleep,” according to Dr. Amy Johnson from University of Pennsylvania School of Veterinary Medicine.7
6. Dolphins can sleep with only half their brains, their brain waves reveal, so literally half of their brain hemisphere is engaged in non-REM sleep while the other half is awake. Consequently, dolphins have three sleep modes: one using the left side of their brain, one using the right side of their brain or fully awake, Scientific American explains.8
7. Vet Street explains what many people have noticed and find quite odd and intriguing: Bats sleep upside down.
“Bats sleep upside down for several reasons: It makes them less obvious prey, and it allows them to take off at any moment should any threat emerge. Bats must fall into flying because their wings aren’t strong enough for them to alight from a standing position.”9
8. Platypuses, which scientists say spend more time in a REM state than any other animal, move when they sleep, and their motions look very much like the ones they make when killing their crustacean prey for food. An account from 1860, which was before REM sleep was discovered, has it that young platypus exhibited “swimming” movements with their forepaws while sleeping.10
9. An albatross can sleep in-flight. Apparently, they aren’t the only avian creatures with this ability. Frigatebirds fly and look for prey to eat over the ocean, but at night, they can switch to slow-wave sleep, or SWS, using both hemispheres of their brain, a phenomenon called unihemispheric sleep.
Some birds sleep with one eye open, with the open eye keeping track of potential predators that may appear. REM sleep is deliberately short in birds, one study notes, lasting only seconds, so they can reduce the risk of being attacked when they are stationary.11
10. Ready for this? A desert snail can sleep, or hibernate, for as long as three years at one time. All Pet News offers more information:
“These creatures need to stay moist to survive, which can be difficult when living in harsh desert climes. Therefore, they bury themselves underground in order to protect themselves until the environment becomes more suitable. They protect themselves in the meantime by sealing themselves into their shells using extra mucus. Their metabolism then slows down and the animals are able to survive off of fat stores until they awaken.”12
There are many fascinating aspects of the animal kingdom, and it’s fun to explore how different animals eat, play, live and, yes, sleep. There’s been a lot of speculation regarding whether or not animals dream, at least in a similar way to humans, and it seems some do.
Cats, in particular, show every indication they’re dreaming, especially in the way they can be observed arching their backs, flexing their claws or seemingly focusing their gaze on unseen objects, all while asleep. It just shows that, awake or asleep, some cats are “living the dream.”