Today, science is leading us in some new and remarkable directions, further blurring the differences between humans and our animal companions. Take sleep, for instance: we know that REM (Rapid Eye Movement) sleep in humans—that highly fluid sleep stage typified by intense brain activity, vivid dreaming, and rapid eye movements —is a critical component of deep sleep. But REM sleep isn’t confined to only humans: signs of it have long been found in dozens of mammals, but more recently in a surprising and expanding group of other creatures: cuttlefish, octopus, rodents, birds, reptiles . . . and even spiders. These new discoveries have prompted some researchers to suggest that dreaming, once believed to be the sole domain of humans, occurs in far more species than we ever thought.

Do Dogs Dream?

Back in the 1800s, the majority of scientists believed that almost all mammals experienced vivid dreams. That vision fell out of favor with the rise of behaviorism in the 20^th century, with many scholars poo-pooing the idea that any species other than humans was capable of dreaming.

Today, we know better, and understand more. As Jane Goodall said, “We find animals doing things that we, in our arrogance, used to think was ‘just human.’”

Which brings us to one of our most enduring companion animals, the dog.  Watch a dog in deep sleep, and you’ll see him twitching and pawing and barking and whining, and if you look closely, you can see movement behind his lidded eyes. Is he dreaming? If so, what is he dreaming about?

Defining Dreams

First, what is a “dream”?  While there is no unified definition of dreaming, the dictionary defines dreams as a series of mental images, emotions, and sensations that occur involuntarily during sleep. Once, scientists believed that dreams arise only during REM sleep, but research over the last 50 years has proven that dreams occur throughout both sleep cycles, although REM dreams tend to be more emotional, vivid, and are longer.

Scientists believe that dreaming is an evolutionary state shared by many species, and serves similar functions such as memory reinforcement, but even they can’t say for certain if our dogs have the same emotional experiences as humans. In many respects their physiology and behavior are similar to ours, leading to the hypothesis that we also share at least some similarities in mental activity, including dreaming.

Exploring Animal Sleep Studies

Yet in most of the 20^th century, while a huge body of scientific studies focused on animal sleep, researchers scrupulously avoided the subject of dreams. Many insisted that the idea of animal dreams was simply anthropomorphizing: the assignment of human traits and emotions to non-humans. It wasn’t until the 2020s that the word “dream” began to enter the lexicon of scientific studies on animal sleep, based in large part on research using EEGs (electroencephalograms), which measure electrical activity in the brain. This revealed that during sleep, a dog’s brain wave patterns are almost identical to ours and exhibit the same type of electrical activity.

Signs That Dogs Dream

Just as humans often exhibit physical reactions during dreams by talking, moaning, laughing, and sometimes sleepwalking, dogs also respond subconsciously to their dreams with physical signs: twitching their paws, wagging their tail, whining, grumbling, licking their lips, and sometimes barking. While all of this cannot prove with absolute certainty that dogs are dreaming, it is the clearest indication thus far that they are.

Unless in the far distant future dogs learn to speak (and what, do you think, would they say?), we need to rely on physical cues to tell us. Lest I be accused of that much-dreaded anthropomorphizing, such assumptions are not so far-fetched: with our fellow humans, we take cues from their physical expressions every day: someone is limping, and we presume they have been hurt . . . someone laughs, we believe something was funny . . . someone grimaces when they bend down, we surmise their back is bothering them. Doctors and mental health experts are taught to watch a patient’s body language, teachers base many of their actions on a student’s behavior, and even our clichés—”watch what they do, not what they say”—reveal just how much we rely on physical signals.

What Do Dogs Dream About?

So, if dogs dream, what do they dream about? Do dogs dream about their owners? Food? Chasing rabbits?

We can only theorize, but it appears they dream about their day. For instance, EEG studies done on rats show they dreamed about the mazes they ran earlier: the rats’ brain activity during sleep was exactly the same as their brain waves while they were running through the actual maze. Researchers could even tell precisely where the rats were in their dream maze. If rats dream of past events, then it stands to reason that dogs, who are more intelligent and whose brains are far more complex, must have similar dreams.

It’s also likely that dogs dream of things that are central to their world, such as food, playing, their human companions, and even more fundamental to the way they experience the world, smelling. Dr. David Peña-Guzmán, author of When Animals Dream: The Hidden World of Animal Consciousness, explains that a canine dream would be far different than a human one, because it would be based upon the unique circumstances of a dog’s life.  Dogs dream on their own terms, and of their own experiences—and since much of how dogs interact with the world is through their noses, it follows that smell is likely a key component of their dreams (unlike humans, whose dreams rarely if ever include smells). A 2025 study goes further, noting that dogs appear to have emotional responses to scents, which only heightens the likelihood that a dog’s dreams would include smells. Since dogs process life through their noses and eyes rather than logically, their dreams probably integrate imaginative events with common scents and sights.

We also know that dogs are capable of experiencing a wide range of negative feelings, including fear and anxiety. Studies on PTSD in dogs reveal that they develop symptoms similar to humans suffering from the disorder, including sleep disturbances, and that the distress from their trauma manifests in their dreams. For dogs with longstanding trauma, such as those with abusive or neglectful pasts, the likelihood of experiencing nightmares may be even higher.

We may never know for certain what mysteries lie within the quiet whispers of our dog’s dreaming mind, any more than they can know what is in ours—but it’s far from fanciful to believe that their dream life is every bit as vibrant, diverse, and emotional as our own.

When your dog walks in circles, it can have many meanings, from nesting habits to neurological red flags. It’s important to look at your dog’s circle of life, including when it’s time to get her to a vet.

An old dog walking in circles can be as endearing as it is concerning. Watching a dog pat down an invisible bed is a throwback to their ancestry. But when that purposeful spin becomes a frantic or persistent, one-way trek, the “why” moves from instinct to anatomy. To understand where to draw the line, here’s look at how a dog’s internal compass—and their brain—functions.

“From a veterinary neurologist’s perspective, circling is a behavior that can mean very different things depending on the context. Many dogs will circle a few times before lying down, which is completely normal and thought to be a nesting instinct,” according to Christian Woelfel, DVM, a veterinary neurologist at Garden State Veterinary Services.

However, Dr. Woelfel adds that “frequent or repetitive circling in dogs, particularly when it consistently occurs in the same direction, can indicate an underlying neurologic problem involving the brain or the vestibular system [the balance center of the nervous system].”

Diagnosing Cognitive Dysfunction Syndrome

For senior dogs, circling can be a symptom of cognitive dysfunction syndrome (CDS). According to Cornell University’s College of Veterinary Medicine, CDS is a “common age-related disease in dogs that affects the brain, causing deterioration similar to Alzheimer’s disease in humans.”

CDS may appear around 9 years of age. “The condition may be underdiagnosed since the behavioral changes progress slowly, and owners may assume that some changes are a normal part of aging,” according to the Cornell report.

“In conditions affecting the brain, you can see additional signs such as disorientation, behavior changes, vision changes, and seizures,” says Dr. Woelfel. “Whereas for vestibular problems [similar to vertigo in humans], circling is often accompanied by a head tilt, loss of balance, involuntary eye movement (nystagmus), and nausea.”

When Circling Is Just Circling

Sometimes circling isn’t about the brain. It’s about the body trying to find a comfortable position for other reasons. “Inner ear infections can cause circling and balance issues as the inner ear is responsible for maintaining a dog’s equilibrium,” says Dr. Chyrle Bonk, an Idaho-based veterinarian.

“Some dogs may learn to turn a couple of circles before they lie down or have a bowel movement. This is usually just their way of getting comfortable and has become part of a routine,” Dr. Bonk adds.

She notes that anxiety in dogs can often mimic the symptoms of cognitive dysfunction. “The best way to distinguish between the two is that anxiety is often situational. Anxiety may be triggered by you leaving for the day, unexpected visitors, or some other change in the dog’s environment, while signs of cognitive dysfunction occur nearly all the time or get more severe around bedtime.”

Dr. Bonk says that circling before lying down is an instinctual behavior dogs use to create a safe, comfortable space to rest. It could also be a dog’s way of clearing the space of obstacles. However, it can also be a sign of a medical condition. “Pain from spinal issues or hip dysplasia can make lying down and getting up difficult and uncomfortable. You may see dogs circling when they start to lie down as they are trying to find the best way to lower themselves without causing pain,” she says.

When Should You Alert Your Vet?

“Turning a few circles before lying down or pooping is considered normal for most dogs,” says Dr. Bonk, “but you’ll want to consult your veterinarian if your dog suddenly starts to circle or if they are circling while doing other things as well. This is especially true if they are showing any other signs of incoordination, anxiety, pain, disorientation, changes in sleep patterns, or behavior.”

Dr. Woelfel concurs, adding that if you notice your dog walking in circles, especially if it occurs suddenly or alongside other neurological signs, it’s wise to see your veterinarian or a veterinary neurologist.

“Veterinary neurologists specialize in disorders of the nervous system and can help pinpoint the cause of circling while guiding the next steps for diagnosis and treatment,” he says.

Checklist: When to Call the Vet

Before calling the vet or neurologist, evaluate your dog for reasons for circling to rule out common physical triggers.  However, contact your vet if your dog falls into one of these categories (based on information compiled from the American College of Veterinary Internal Medicine, Cornell University College of Veterinary Medicine and the UC Davis Veterinary Medical Teaching Hospital, the International Association of Animal Behavior Consultants, American Animal Hospital):

• Sudden Onset: The circling started overnight.
• One-Way Street: Your dog turns only in one direction.
• Nystagmus: Your dog’s eyes are flickering or darting back and forth.
• Circles With No Purpose: Your dog isn’t circling to nest but rather seems stuck or lost in corners.
• Physical Distress: Paired with a head tilt, nausea, or crying out when trying to lie down.

Of the six dogs I’ve adopted over the years, three of them had dramatic “who is that dog in the mirror” incidents.

There was the time a clerk at an upscale Newbury Street store in Boston nicely suggested that my black Labrador, Solly, and I leave after he caught a glimpse of himself in the mirror and had a meltdown.

Then there was the time my yellow Lab, Daisy, horrified me when she glanced up at a mirror in an elevator ceiling and suddenly started barking, snarling, and growling. I thought something demon-like was crawling above us.

Speaking of demons, the first time my pup, Macy, looked in a mirror, she made noises like she was possessed.

Why do some dogs have such distinct reactions when they see their reflections? Do dogs recognize themselves in the mirror? Do dogs understand mirrors? Figuring out the answers to these questions has been a hot topic for animal researchers.

Do Dogs Recognize Themselves in the Mirror?

Dr. Stanley Coren, professor emeritus in the Department of Psychology at the University of British Columbia and an esteemed researcher and writer about the intelligence of dogs, has his own stories about pups and mirrors. One of his favorites occurred when a friend offered to dog-sit a male Cocker Spaniel at her home.

“When she opened the door to the bedroom, the visiting dog stopped and looked at his image in the mirror and then walked over very deliberately and ‘raised his hind leg’ (urinating) on the mirror, and on himself,” Dr. Coren recalls with a chuckle.

But what was that dog thinking? Dr. Coren and other scientists have concluded that dogs do not recognize themselves in the mirror, believe their reflection is likely another dog, and eventually lose interest.

“The reason they lose interest is that the reflection doesn’t smell, it has no scent,” Dr. Coren says. “It looks like a puppy, but it doesn’t smell like a puppy, and it doesn’t interact with them the way that a real puppy would. There’s no evidence that dogs ever develop the sense that the image they’re looking at is themselves, and for some researchers, it is a very important fact.”

Important because of the ongoing discussion about whether dogs are self-aware. It’s something that scientists, dating back to Aristotle, have pondered.

Are Dogs Self-Aware?

Over the years, researchers identified three different levels of animal self-awareness.

The first, or basic, level is sentience, which means an animal is aware of their environment and sensations such as hunger and pain. Most animals have this level of consciousness.

The next level of awareness is the ability to remember and to learn from experiences.

The highest level of consciousness is recognizing oneself.

Researchers have used what’s called “the mirror-mark test” on many animal species to see whether they are self-aware enough to recognize themselves in the mirror.

In 1970, researcher Gordon Gallup Jr. tried the first test on chimpanzees.

“Chimps very quickly recognize themselves in the mirror; they make faces in the mirror, it amuses them,” Dr. Coren says.

But while the chimps Gallup was working with were sleeping, he put visible red marks (using harmless dye) on their faces.

“When the chimps woke up, looked into the mirror, and saw there was this red spot in the middle of their forehead, they recognized that that was themselves, and they reached over and tried to touch that spot because it was on their head,” Dr. Coren says.

Dolphins, orcas, Asian elephants, some birds, and fish have passed the mirror test, but do dogs pass the mirror test?

Unfortunately, as smart as our favorite four-legged friends are, when scientists tried it with dogs, they didn’t notice the spot on their heads.

Does this mean dogs do not reach the highest level of self-awareness? Are dogs conscious? Have some faith in our four-legged friends; this story isn’t over. Researchers didn’t give up.

Stumped by the dog mirror tests, scientists had an inkling that dogs just had to be more self-aware, so they tried other experiments to prove it, using one of dogs’ greatest senses: smell.

Sniffing Their Way to Self-Awareness

In 2021, evolutionary biologist Marc Bekoff, now a professor emeritus at the University of Colorado Boulder, published what’s referred to as “the yellow snow study.”

If you’ve ever walked a dog in the snow where other dogs have relieved themselves, you know how those yellow spots are golden sniffing material for a pooch.

Knowing this, Bekoff had a hypothesis, one that his dog Jethro helped him prove. For five winters, Bekoff scooped up the yellow snow Jethro marked and moved it to different locations on a trail. He also collected yellow snow that other dogs marked, moved it around, and observed Jethro.

“When his dog encountered a yellow spot made by another dog, he would pay a lot of attention to it, but when he encountered a spot stained by his own urine, he would pay a lot less attention,” Dr. Coren says. “So Beckhoff concluded that dogs do have that sense of ‘this is me.’”

Another scientist, Alexandra Horowitz, a Barnard College dog cognition expert, doubled down on Gallup’s and Bekoff’s research.

She created an “olfactory mirror” experiment using samples of a dog’s own urine and also samples of a dog’s own urine combined with an added scent.  She found that the dogs spent more time sniffing the scented urine, suggesting they noticed their scent had changed, which shows self-awareness.

What is Dr. Coren’s opinion on dog self-awareness? He looks back to one of his heroes, Charles Darwin, who thought there was no reason animals couldn’t have consciousness, though it may not be as complex as in humans.

“The data has been coming out showing that dogs have an emotional range equivalent to a human toddler of about two and a half years of age,” Dr. Coren says. “Dogs don’t have the full range of emotions that humans have, but they have all the basic emotions: joy, fear, anger, that sort of thing. But dogs don’t have the complex social emotions like guilt and pride, which don’t show up in humans until at least four years of age.”

But of course, since dogs can’t talk, it’s tough to know exactly what they’re thinking.

So what does a dog think when they’re barking up a storm in a mirror, as my dogs did? Dogs having reactions like those may not seem like their most brilliant moments, but they just navigate the world a bit differently than we do.

Anyone who has ever walked a dog knows their nose leads the way as they sniff along, trying to make sense of scents. One of my friends calls it “dogs checking their pee-mail.”

There’s still so much to learn about dogs, though they seem to have a pretty good read on us, much of it through smell.

Dogs have between 100 and 300 million scent receptors in their nose, which they use to recognize not only themselves and other dogs, but also their humans. They can even sniff out our emotions, physiological changes, and even types of cancer.

Perhaps the fact that dogs don’t recognize themselves in the mirror further proves how selfless they are; they don’t need a mirror, they already know they’re quite incredible.