Home / Why Do Dogs Wag Their Tails While Sleeping?
Fine By Breed Name

Explore By Characteristic or Group


Find Your Match

Answer a few simple questions and find the right dog for you

Compare Breeds

Compare up to 5 different breeds side by side

Find a Puppy

Nunc bibendum, purus eget tristique fermentum.

Choose your Breed

View the collection of dog breeds we have information on.

Why Get a Dog?

Nunc bibendum, purus eget tristique fermentum.


Aenean feugiat metus ac nisi dictum tincidunt Interdum et.
Exclusive Deals, 50%+ Off Good & Toys, Health Information & More!

Why Do Dogs Wag Their Tails While Sleeping?

Can you recall your dream from last night? Probably not. Most of us don’t remember what our dreams are about, nor do we recall if we’ve been tossing and turning, sleepwalking, or even talking.

But, it’s not only your own brain that drifts off into dream-land while you sleep. Your dogs do, too.

Perhaps he is dreaming about that last treat you gave him before bed. And, if he is, his tail just might be swinging back and forth while he’s dreaming.

Why do dogs wag their tails in their sleep? Dogs wag their tails in their sleep because they are in a state of deep sleep. Just like us, they experience what is called “Rapid Eye Movement” (REM) during their deepest stages of sleep. It is during REM sleep that dreams occur, and dogs are not so far removed from our own evolutionary developments.  Thus, scientists have concluded that similar to humans who dream during this deepest stage of sleep, dogs also spend their most restful sleep time in the REM stages.

Often these stages result in dream-like behavior, which can include twitching, barking, and even tail wagging (source).

Read on to learn more about what your dog’s sleep habits say about him and what he might be trying to communicate with you with that swinging tail. 

Dogs and Dreaming: Why is Your Dog Wagging Its Tail While Sleeping?

Dreams are an inexplicable mystery to most of us, and not even science can affirm the reasoning behind most of our dreaming habits or why we do certain things while we are sound asleep.

Just like us, dogs probably dream quite a lot during their daily slumbers. And, just like us, they do things in their sleep unbeknownst to them, such as tail wagging, in the same way, that we may walk and talk while we are fast asleep without knowing it. 

And, similar to our own ways of communicating via talking or facial expressions, a dog’s tendency to wag his tail accomplishes the same purpose, whether he is awake or asleep. 

Why Do Dogs Wag Their Tails?

Why Do Dogs Wag Their Tails

To really understand why dogs wag their tails in their sleep we first need to establish the deeper reasons why they wag their tails at all.

You’ve likely noticed your dog wag his tail quite a lot, especially when he is excited about something. But you’ve probably not thought too much about it, except to know that his wagging tail is certain to make you smile. 

But there are multiple reasons why dogs wag their tails, and it’s not only to communicate joy.

There is a practical joke prank box out there called “Pet Talk.” Its label reveals that with a special “animal translator collar,” you can understand what your pet is trying to tell you.

It even claims to allow you to add in voice control, personalizing your pet’s voice to your liking as it translates his barks into words. 

Haven’t we all, at times, wished our dogs could talk to us and tell us what they’re thinking and feeling?

The reality is that they do! Sure, they may not be able to talk, but if you look and listen closely, your dog communicates quite a bit, whether it be through barking, body language, or tail wagging. It’s our job to listen.

Tail Wagging – It’s Similar to Making Facial Expressions

Think about the last time you smiled. What were you communicating? Happiness?  Nervousness? Joy or Excitement? Or, was it a bit of sarcasm?

There are millions of expressions we make with changes to our eyes or the shape of our mouths, and each of them communicates a particular emotion. It’s up to others to interpret our expressions and, we hope, act accordingly.

Similarly, a dog’s tail is his best way of communicating with other dogs (and people) since dogs are incredibly adept at sensing movement.

A swinging tail can mean a lot of different things, just as a smile doesn’t always reflect simple happiness. Tail movement and position can each act as an indicator of your dog’s mood.

Tail Positioning and Direction

Tail Positioning and Direction

The position of your dog’s tail, as well as the direction and speed in which it is swinging, could indicate a range of emotions, including fear, anxiety, guilt, or pure and simple joy.

A dog who is wagging his tail but simultaneously exhibiting other signs reflective of agitation or fear can easily be mistaken as friendly when his body language communicates otherwise. 

Anxiety or Fear

If your dog is holding his tail lowered and in between his legs, it’s likely that he’s not feeling very comfortable, even if his tail is wagging.

He may be anxious or afraid, depending on his surroundings or other signs he is giving with his body languages, such as piqued ears or tense positioning.  

A slow tail wag is generally not indicative of a dog who is happy. Rather, he may be communicating fear or perhaps submission. Or, he could be feeling guilty for tearing up your favorite pair of slippers. 

If you notice a slow-moving tail, try to reaffirm your dog and let him know he’s okay, even if he’s done something wrong.

Remember, whether it be your favorite pair of shoes or the couch cushions that he’s chewed, if your tone is clearly one of anger or frustration, your dog will sense that, and his tail will respond in kind.

It’s important to consider that dogs don’t create master plans to chew on your prized possessions – they are simply acting out of instinct and need to be taught the difference between your toys and theirs.

With that in mind, it’s always best to avoid causing feelings of fear or anxiety in your dog based on his poor behavior.  You can read more about positive training methods for dogs who are chewing or nipping in the article titled, “My Dog Won’t Stop Biting Me.

Curiosity and attention

A tail standing more erect than normal likely means that your dog is curious or focused on something – perhaps waiting for you to throw the ball to him. His attention is high, and he is alert, anticipating his next move.

Some dogs are uniquely adept at identifying objects or prey by pointing at them with their paws, and simultaneously, holding their tails up high in the same way that you might stand more erect when you are trying to listen closely or hear something someone is saying. 

These “pointer” dogs may also do these same things while they are sleeping, especially if it’s a habit they’ve been trained to do during the day while awake.

If you’d like to learn more about the features and abilities of these types of dogs, you can read more about them in the article titled “Dog Breeds Who Use Their Paws A Lot.


The common turn of phrase, “wag more, bark less” is a simple expression hoping that we’ll all be a little friendlier toward one another. A wagging tail that swings energetically is usually a friendly greeting or reflective of excitement. 

You’ll notice that his tail is moving quickly back and forth from side to side.  He may even start turning in circles trying to chase it, too. These are all signs that your dog is a happy camper and excited to see you.    

Right Versus Left Tail Wagging

Interestingly, the direction in which your dog is wagging his tail could also be reflective of his mood. If you notice that your dog is wagging his tail more toward the right side of his body, he is more likely to be feeling relaxed and at ease. 

On the contrary, if he is wagging his tail more toward the left side, it is more likely that he is feeling either on alert or anxious about something (source). 

If this is the case, his tail is likely moving a bit more slowly than if he were feeling excited, so pay close attention and try to determine what your dog is trying to tell you. 

For a quick recap, here’s a short video:

Canine Sleep Habits – Dreaming During REM Sleep

Canine Sleep Habits

We already know that dogs sleep a lot, especially during the day when there’s not much else going on. And, scientists seem to agree that while they are fast asleep, dogs also dream quite similarly to the way that we do, often replaying things that have happened throughout their day (source).

How Do We Know Dogs Dream?

Scientists at MIT have conducted experiments measuring brain activity in rats while they perform specific tasks, such as running, while asleep. They then compared that brain activity to the brain activity that these rats exhibited while sleeping. 

The results showed that the brain waves were nearly exact while asleep as when awake, leading to the belief that even rats dream about their daytime activities (source).

It’s easy to conclude, then, that if rats are dreaming about running through mazes while sleeping, it’s quite likely that dogs, having more sophisticated brains, are also dreaming. 

When Do Dogs Dream?

As mentioned earlier, our most restful sleep occurs during REM sleep. This is when we are most soundly asleep, and getting much-needed rest from a busy, active day. It’s much more difficult to wake someone from REM sleep – breathing is deeper, and restoration is in full effect.

The same is true for our pets. During REM sleep, your dog is getting the deep rest he needs from all that intense playing at the dog park. REM sleep can happen any time he is napping, whether day or night.

You might notice that your dog’s eyes are moving a bit during REM sleep – you may even see is eyelids twitching a bit. If so, try not to stir your dog. Just as it would be startling for you to be woken from a deep sleep, the same holds true for your pet.

What’s He Dreaming About?

The short answer is, who knows? But, consider your own dreams. Often, our dreams consist of things that happened during the day, whether something worrisome or something good that happened.

He may be dreaming about chasing a ball, or he may be dreaming about something else, such as a fear, or not getting your left-over dinner!    

A dog’s emotions aren’t all that different from our own, in the general sense. They, too, feel fears, worries, anxieties, and happiness.

Final Thoughts

Remember, dogs are man’s best friend for a reason. They’re hoping to make you happy, and they’re also hard at work trying to communicate with you through their movements and unique expressions. Their brains work quite like ours, even if on a lower level of sophistication.

So, next time your dog is asleep, take a closer look at what he’s doing, and the movements of his tail, too! If you pay close attention, you might even be able to guess what he’s dreaming about! 


Submit a Comment

Your email address will not be published. Required fields are marked *