Do Animals Sleep Like Humans? Animal Sleep Explained

Have you ever watched your dog twitch and whimper in its sleep and wondered what it was doing in there? Or seen a bird tuck its head under a wing and thought, "That looks a lot like bedtime"? It's a fun question: do animals sleep like humans?

The short answer is yes and no. Many animals sleep in ways that look a lot like us. But some do things that sound made up, like sleeping with half a brain, napping in mid-air, or going to sleep for the whole winter. Scientists are still working out why.

In this post, we'll look at animal sleep patterns and how they compare to ours. We'll cover what happens in the brain, who gets REM sleep, whether animals dream, and why some animals sleep for 20 hours while others barely sleep at all. We'll keep it simple and stick to what researchers have actually found.

Do Animals Sleep Like Humans?

Let's start with how we sleep. Humans usually sleep in one long block at night. During those hours, we move through repeating cycles of about 90 minutes each. Each cycle has lighter sleep, deeper sleep, and REM sleep, which is the stage linked to vivid dreams. Most adults need at least seven hours a night.

Now look at the rest of the animal world. Some animals share our pattern of lighter and deeper sleep. Others split their sleep into many short naps through the day and night. And some have found clever ways to sleep that we can't copy at all.

Here's a quick side-by-side look:

What Happens in the Brain During Animal Sleep?

Scientists learn about animal brain activity during sleep by using the same tool they use on people: small sensors that pick up the brain's electrical signals. When we're awake, those signals look quick and busy. In deep sleep, they turn slow and rolling. In REM sleep, they speed up again and look a lot like waking brain activity, even though the body is resting.

That's the classic pattern in mammals and birds. Something similar has been found in some other animals, too. In bearded dragons, which are lizards, researchers saw a stage that looks like REM. Zebrafish seem to have two sleep states. One looks like the deep, slow sleep of mammals, and the other looks like waking brain activity.

Why sleep seems to matter so much

Scientists have found sleep-like rest in animals as simple as fruit flies and jellyfish. Upside-down jellyfish, for example, move their bells about one-third as often at night. When they're kept awake at night, they get less active, as if they need to catch up. That tells us sleep is very old. It probably did something important for animals long before humans showed up.

We don't know every reason yet. But in people and animals, sleep seems to help the brain and body rest and reset. That's one big reason researchers keep studying it.

Do Animals Have REM and Deep Sleep?

Many do. REM sleep was first spotted in human babies back in 1953. After that, scientists found it in cats, mice, horses, sheep, opossums, and armadillos. Birds have it too. You might see their bills and wings twitch while they sleep.

Not every animal fits the same mold, though. In an article from Knowable Magazine, scientists describe REM-like sleep in cuttlefish and octopuses, where the skin changes color during these bouts. Researchers have also seen REM-like eye movements in jumping spiders, about every 17 minutes in one study of 34 spiders. But scientists haven't confirmed that the spiders are truly asleep, so that one is still an open question.

Dolphins and whales are a special case. Reports suggest they may not have REM sleep at all, or very little of it. Their deep sleep happens in a very different way, which we'll get to in a moment.

Do Animals Dream Like Humans?

This is the question everyone wants answered, and the honest answer is: we don't know for sure. Animals can't tell us what they dreamed about. And scientists point out that no single clue proves dreaming.

But there are some interesting hints. Mice that ran through a maze showed brain firing patterns during sleep that matched the places they had been. That may be a kind of replay of the day. In pigeons, brain scans showed that many of the same areas that light up during human REM sleep also light up during bird REM. Pigeons' pupils also shrank during REM in a way that looks like what they do when they're courting, which makes some researchers wonder if the birds were reliving that moment.

A good way to put it: animals clearly have REM-like sleep, and their brains seem busy during it. Whether that adds up to dreams like ours is still being debated.

Why Do Different Animals Need Different Amounts of Sleep?

This is one of the biggest puzzles in animal sleep science. Look at how much sleep different animals get, and the gaps are huge:

These are rough numbers, since they come from different studies and animals. But the big picture is clear. So why the big differences? Scientists have a few ideas.

Do animals sleep at night or during the day?

It depends on the animal. Some, like bats and many owls, are active at night and sleep by day. Others, like deer and rabbits, are busiest around dawn and dusk. Most of these timings are guided by an inner body clock called the circadian rhythm, which works in animals much like it does in people.

The clock isn't only about light, though. In the elephant study, researchers found that things like temperature and humidity, not sunlight, seemed to affect when the elephants went to sleep and woke up.

Do all animals sleep every day?

Almost every animal that scientists have studied shows some kind of sleep or sleep-like rest. But not all of them do it the same way every day. Wild elephants can go up to 48 hours without sleep when they are in danger from predators or hunters. They can also walk as far as 30 kilometers to get away. And elephants only seem to lie down about once every three or four days, for around an hour at a time. Scientists think that's probably when they get their REM sleep.

How Do Dolphins and Birds Sleep Differently?

Now for the best part. Why do dolphins sleep with half their brain? The answer comes down to breathing. A dolphin has to choose to come up for air. If its whole brain shut off, it could drown. So it rests one half of its brain at a time while the other half stays awake to control breathing and watch for danger. Scientists call this unihemispheric sleep, which just means "one half of the brain sleeping."

Dolphins aren't the only ones. According to Scientific American, northern fur seals sleep with half a brain while they're in the water, but with the whole brain when they're on land. Many birds can do it too, including pigeons, mallard ducks, and blackbirds.

Can animals sleep with one eye open?

Yes! It's real. Mallard ducks show a great example. Ducks on the edge of a group, where it's riskier, do much more of this one-eyed sleep than ducks in the middle. The open eye faces outward, like a tiny lookout. Humans don't do true half-brain sleep, but there's a small hint of something similar. When people sleep in a strange place, one side of the brain tends to stay lighter and easier to wake, which is sometimes called the first-night effect.

How birds sleep compared to humans

Most birds sleep on a perch at night, and many of them have REM sleep like we do. But the great frigatebird has a trick no human could do. A team from the Max Planck Institute for Ornithology put small recorders on frigatebirds in the Galápagos, and published their results in 2016. They found the birds sleep while flying for days over the ocean. In flight, the frigatebirds slept only about 42 minutes a day on average. Back on land, they slept for over twelve hours a day.

In the air, they often slept with one half of the brain at a time, and their REM sleep bouts were super short, lasting only seconds. That's quite a different "bedtime" from ours.

Do Wild Animals Sleep Deeply or Stay Alert?

For many wild animals, sleep is a balance between rest and staying safe. Deep sleep is great for the body, but it also makes an animal an easy target. That's why so many animals have found ways to stay a little bit alert.

• Sleeping lighter or less. Animals that are hunted, like deer, tend to get less sleep than animals that are rarely hunted.
• Taking turns. In groups, some animals keep watch while others rest. Mallard ducks use the edge-of-the-flock trick we just talked about.
• Half-brain sleep. Dolphins, fur seals, and some birds keep part of their brain awake.
• Skipping sleep when needed. Elephants have been seen staying awake for up to 48 hours when they sense danger.

So when you hear someone say an animal "sleeps like a log," that's not how most wild animals do it. They're usually sleeping with one ear, or one eye, or half a brain on the lookout.

Hibernation: is it the same as sleep?

Not quite. According to wildlife writer JV Chamary at Discover Wildlife, hibernation and a shorter state called torpor are deeper and more dramatic than sleep. Daily torpor lasts a few hours, and hibernation lasts days or weeks. During daily torpor, an animal's body temperature can drop from around 38°C to around 18°C. In hibernators, the average body temperature is closer to 5°C, and the body uses far less energy.

Here's a surprising twist: animals that hibernate can still get sleep-deprived. Scientists think this suggests that some jobs of sleep, like helping with learning and memory, may need a normal body temperature to work. That's why hibernating animals wake up now and then. Large hibernators like black bears burn stored body fat and don't eat or drink during the winter.

What Can Scientists Learn From Animal Sleep?

Studying how animals sleep isn't just a fun hobby. It helps answer some big questions:

• Why do we sleep at all? If animals as different as jellyfish, birds, and dolphins all do it, sleep must be doing something important.
• What is REM sleep for? Wild elephants seem to get REM only every few days, which doesn't fit the idea that REM is needed every night to lock in memories. That's the kind of surprise that sends scientists back to the drawing board.
• How can a brain rest and stay alert? Half-brain sleep shows that the brain can run two modes at once, which may teach us more about how sleep is controlled.
• Why does the same species sleep differently in the wild and in a zoo? This shows how much safety, food, and surroundings shape sleep.

What does this mean for your own sleep?

Humans are lucky in one way: we can usually sleep deeply and all in one go, because most of us don't have to watch out for lions. That's also why good sleep habits matter so much for us. A steady bedtime, a dark and quiet room, and a calm wind-down all help our bodies do what they're built to do. Some people like to add a sleep supplement to that routine. If that's you, Oek Somnia Sleep Gummies are made for the bedtime routine. Check the label for ingredients and directions before you start.

Frequently Asked Questions