Why Do Dogs Wag Their Tails In Their Sleep? (Explained)

Have you ever noticed your dog wagging its tail while sleeping? You were comfortably snoozing on the sofa, and suddenly your dog starts wagging its tail even more enthusiastically than when you offer a juicy treat. It is both weird and funny, right? 

To better understand the dog’s tail wagging during sleep, we will separately review and explain both the sleeping and tail wagging behaviors in dogs and answer some popular questions on the topics.

Why Do Dogs Wag Their Tails In Their Sleep

So, why do dogs wag their tails in their sleep? Well, simply put, dogs wag their tails while sleeping because they have happy dreams. Just like us, when in the deep sleep state, dogs go through the REM (rapid eye movement) phase, and the REM phase is when dreams occur. In fact, tail wagging is not the only thing dogs can do while sleeping. Depending on the dream, some dogs can twitch, bark, grunt, whine, paddle with their feet, or even cry. 

The Dogs Sleeping Cycle Explained

dog sleeping cycle

Unlike the human’s binary sleeping pattern, dogs follow a so-called polyphasic sleeping pattern. The binary sleeping pattern means humans spend 12 hours awake and then sleep for eight hours. 

The polyphasic sleeping pattern indicated dogs sleep in short bursts irregularly scattered throughout the day. For example, a dog can sleep for 10 minutes and then spend 2 hours awake and vice versa. 

Estimations show dogs spend 50% of the day sleeping. The other 50% are divided between being awake but lying around and being physically active. 

The sleeping patterns are different but the phases are the same and include:

  • Phase 1 or slow-wave of sleep – when the breathing, heart rate, and blood pressure decrease 
  • Phase 2 or rapid eye movement (REM) – the deep sleep phase in which the eyeballs move rapidly beneath the leads. The REM phase lasts around 10 minutes. 

Because of the irregular sleeping pattern, not every dog nap involves the REM phase. A dog can fall asleep and wake up without entering the deep sleep phase. That is why dogs need more sleeping time than people. 

So, to get back to the main question – why do dogs wag their tails in their sleep? Dogs wag only when in the REM phase because dreams are only possible during deep sleep phases. 

If your dog starts wagging its tail while sleeping, it means it is well-relaxed and dreaming of something nice and worth wagging.

What do dogs dream about?

When dogs dream, they are usually replaying their everyday activities like eating, playing, chasing. For example, a German pointer will probably dream about hunting birds, a Collie about herding sheep, and a Doberman about chasing thieves. 

In general, dogs that like being physically active can dream about retrieving balls, swimming, or hiking. In contrast, dogs that prefer sedentary lifestyles are more likely to dream about curling in front of the TV or cuddling with the owners.

Interestingly, the dog’s size influences the dream’s length. For unknown reasons, small dogs tend to have shorter dreams but more frequently. On the other hand, larger dogs dream less frequently, but their dreams are longer when they do.

Can dogs have nightmares?

dogs have nightmares

Yes, dogs can have nightmares. Dogs can dream about situations that make them anxious, like visiting the vet or groomer or watching their owners play with other dogs. Rescue dogs can even have nightmares about their pre-rescue lives.

Your dog’s body language can reveal a lot about whether your dog is having pleasant dreams or nightmares. Happy dreams are usually accompanied by a soft paw and eyelid twitching, ear flicking, and tail wagging. 

Nightmares are accompanied by howling, whimpering, whining, barking, grunting, intense led paddling, and even sudden jerking. 

Dogs should not be woken up while having a nightmare because they can react badly out of the confusion the bad dream made. However, if the nightmare lasts for several minutes and you like to end your dog’s terrible dream try waking it up using your voice. Touching it would be too stressful for your dog and dangerous for you. 

If your dog is prone to nightmares, make sure you create a more comfortable and relaxing sleeping environment – a memory foam mattress, light music, and a massage or two.

What sleeping position says about your dog?

Your dog’s sleeping position can say a lot about your dog – how it feels and what it needs. Here are some of the most common sleeping poses in the canine world. 

The doughnut

This position is charming – your dog will be curled up in a little ball with the nose closely touching the tail. This position is a remnant from the dog’s wild ancestry.

Namely, dogs and wild canines prefer this position because it helps regulate body temperature by conserving heat; it protects the belly and vital organs; and makes it easy to jump if necessary. 

A dog that is always sleeping in the doughnut position might feel insecure about its environment or is trying to keep itself warm. In such cases, you should try creating a more secure environment and invest in a self-heating bed or a bed with wraparound well-padded bolsters.

The Superman

This is one of the funniest positions – it literally looks like your dog is Superman while flying. In other terms, the dog will have its belly stretched with the legs spread out. 

Small breed dogs and puppies enjoy sleeping in this position. However, even big dogs can practice the Superman position, especially if they are hot and trying to cool themselves. 

A dog that is always sleeping in this position might be trying to tell you it needs an elevated bed, preferably made of breathable mesh fabric.

The sunny-side-up

In this pose, your dog will be sprawled out on its back with an exposed belly and legs up in the air. Wild dogs rarely practice this pose because it exposes the most vulnerable part and makes sudden jumping and getting up really hard. 

The sunny-side-up is also good for cooling because the belly fur is thin and allows heat release. The sweat glands are up in the air, thus helping with the cooling.  

If your dog is a fan of this position, get it a gel-cooled bed. Alternatively, you can get a lounger bed that offers extra support to the back. 

The side-sleeper

Just like you, your dog enjoys sleeping on its side. Medium and large-sized dogs often sleep on their side with the legs well-extended. This position means they feel safe, comfortable, and relaxed. 

If your dog is often side sleeping, you need to look into beds that allow burrowing and bed with foam mattresses for extra support. 

The snuggle bug

Dogs that love cuddling with you or other pets during sleep time miss their puppyhood days when they slept together with the mothers and littermates. A grown dog that enjoys the snuggle bug sleeping position demonstrates its feelings of love, trust, and affection. 

If your dog is a snuggle bug, try spending as much time as you can snuggling with it or invest in a snuggery-style, self-warming sleep lounger bed that allows burrowing.  

Finally, keep in mind your dog’s favorite sleeping position is the one that includes you and your bed. Dogs that snore and drool are not the ideal sleeping partners, but they are adorable. 

Do dogs pretend to sleep?

dogs pretend to sleep

As funny as it seems, the answer is yes, dogs can pretend to sleep. Dogs usually pretend to sleep when trying to avoid something they do not particularly enjoy. For example, some dogs pretend to sleep when they hear the word “bath” or the name of their vet. 

Watching a dog pretend sleep can be funny, considering not all dogs are equally good at this. Some dogs may even pretend to sleep with one eye wide open so they can see whether their act fools you. Alternatively, they can keep their ears pricked up to hear if you are approaching to “wake’’ them up. 

Even a skilled sleep pretender can be tricked into stopping its pretend mode. All you need to do is say something your dog really loves, like “walk time” or juggle the treat bag your dog cannot resist, and the fake sleep is over. 

Keep in mind that not all dogs fake sleeping. Some are couch potatoes and simply love sleeping. Therefore, before you blame your dog for pretending to sleep, make sure it is not just dozing off and lightly snoozing.


dog tail wagging in sleep

To understand why dogs wag their tails in their sleep, we need to go deeper and explain why dogs wag in the first place. 

People are good listeners, and dogs are good watchers. That is why people communicate with words and dogs with tails. Today, dog tails come in an array of shapes and sizes. That is part of the canine evolution – nature’s attempt to improve the communication between dogs. 

Just because dogs do not use complex words when talking, it does not mean their “tail language” is simple. In fact, the tail’s position and wagging speed say a lot. You just need to observe carefully. 

The dog’s tail position indicates:

  • Agitation: the tail and the ears are both held up
  • Negotiation: a wagging tail that suddenly stops means the dog does not want to be aggressive but prefers not to engage in further communication
  • Aggression: when the tail moves from neutral to vertical positioning, it means the dog is prepared for attack and defense
  • Submission: when the tail moves from neutral to lower or between the hind legs, it means the dog is submissive and asks not to be harmed. 
  • Curiosity: the tail is held horizontally 
  • Happiness: the tail is slightly raised or in a neutral position. 

The dog’s tail wagging speed indicates:

  • Excitement – the faster the wag, the happier the dog. Some dogs can wag so fast it looks like their tail are vibrating. 
  • Insecurity – slight and subtle tail wags mean the dog is uncomfortable or insecure in the given situation. 
  • Friendliness – free tail wagging accompanied with hip wiggling is an invitation for interaction. 
  • Aggression – a dog that is wagging its tail really fast while keeping it up represents a threat and does not want to be petted.  

Why does my dog wag his tail when he lays down?

A dog wags its tail in an effort to communicate with you or the environment. In simple words, tail wagging is the canine equivalent of facial expressions in people. 

If your dog lays down and wags its tail, it might be inviting you to join or pet it so it will feel better. If your dog lays and starts wagging just after you came back from a long run in the park, it might be happy it is back home. 

Learning your dog’s overall body language can be a tricky task and requires time and patience. 

What does it mean when a dog wags its tail from side to side?

dog tail wag from side to side

Enthusiastic side to side wag usually means a friendly greeting, something like your dog saying, “I am so happy to see you.” 

study published in 2003 suggested that the side towards which the wag leans says a lot about how the dog feels. In a nutshell, if the dog is wagging more towards the right side of its body, it means it is happy, joyful, and relaxed. On the contrary, if it is wagging more on the left, it is stressed, anxious, and alert. 

Do dogs talk (wag) to themselves?

To communicate, we use words, and dogs use their tails. However, unlike us, dogs do not wag their tails or talk to themselves. They wag when communicating with us, other people, and other dogs, but they never wag when alone. 

So, if you have the habit of muttering to yourself when someone annoys you, rest assured your dog is not muttering to itself when you interrupt it in the middle of its furniture chewing session.


When it comes to dreaming – both concept and evolution, dogs are not that far behind us. Both the dog’s and the human’s sleep cycle, although following different patterns, feature the same REM phase in which dreams are possible. So, dogs wag their tails in their sleep for the same reason we move our hands or legs in our sleep – the dreams. 

Therefore, the next time your dog starts wagging its tail in its sleep, you can assume it is doing something exciting and fun, like playing with you or walking around with a juicy bone in its mouth. 

All in all, dreaming is similar in humans and dogs. However, what differs is the type of dreams – it is improbable for us to dream about chewing bones.


Dog wagging tail dream meaning?

Seeing a dog wagging its tail in your dreams is a good sign indicating group acceptance and healthy social life. In our dreams, dogs are usually seen as a symbol of protection, loyalty, and generosity. 

Should you wake a dog from a bad dream?

No, waking up a dog that is having a bad dream can be dangerous. Just like in people, confusion after dreaming is normal in dogs. A confused dog may react adversely to being forcefully woken up. 

Why do dogs like to sleep with you?

There are many reasons why your dog likes to sleep with you including, offering or seeking protection, looking for more comfortable sleeping conditions, or simply trying to reinforce your bond. 

Do dogs dream about their owners?

Since dogs tend to dream about things they like, they can dream about their owners – interactive activities, the owners’ faces, or smells. 

Can tailless dogs communicate?

Tailless dogs are capable of limited communication with each other. If the tails are gone, dogs can communicate using facial expressions, ear positions, and body stances.