dog sleeping

It’s pretty common for humans to sleep with their eyes slightly open, but what about dogs? Is it a reason for concern? Or should you just let your pet canine continue sleeping this way?

A dog sleeping with eyes open is relatively common, and most of the time, it’s not a reason to worry. However, some exceptional cases could signify a medical condition.

If you’ve noticed your dog’s eyes are open when it’s asleep, then this is the right place for you. We’ll talk about some of the most common reasons why your dog may be sleeping this way, as well as some medical conditions that may be the culprit.


Evolutionary Purpose

Your dog sleeping with its eyes open could be the result of evolution, and it’s an evolutionary survival strategy of many other species.

Experts don’t know why certain dogs sleep this way, but it’s speculated that dogs do this to enable them to remain alert to potential predators and dangers in their environment.

In some cases, especially in the wild, eyes that are wide or partially open can scare off predators thinking the dog is still alert even when it’s asleep.

This explanation is the most rational and most common reason a dog may sleep with its eyes open, but many other possible causes exist.


Other Possible Reasons Why Your Dog is Sleeping with Eyes Open

Here are three possible simple reasons why your dog may be sleeping with its eyes partially open:

1. Your Dog May Have Woken Up Briefly

Humans enjoy a 90-minute sleep cycle wherein we wake up and drift back to sleep again in a long sleep cycle. However, for dogs, it’s a mere 20 minutes. If you see your dog lying down in its dog bed and its eyes are wide open, your dog could have woken up briefly before getting back to sleep.

2. You’re Seeing Your Dog’s Third Eyelid

Dogs have a third eyelid that keeps their eyes moist and removes dirt and dust that land on the surface of their eyeballs. This eyelid is called the nictitating membrane, and it sits below a dog’s normal eyelid.

When dogs open their eyes while sleeping, this 3rd eyelid remains in place, so what you may be seeing is the nictitating membrane and not the eyeball.

3. Your Dog is Dreaming

Your dog could be in a deep sleep state, and it’s partially opening its eyeball in response to what’s happening in the dream. Open eyes may also be accompanied by twitching their legs, serving evolutionary purposes when dogs are left vulnerable during deep sleep.

Related: Where should my dog sleep at night time

4. Your Dog’s Breed

Many dog owners and vets notice most dogs with very long or very flat faces often sleep with partially closed eyes. Some brachycephalic dogs that have been specifically bred are losing their ability to close their eyes fully.

What happens with dogs with flat faces is that their eyes protrude far from their socket, and the lids can’t completely close.

Though sleeping with eyes partially open is common for dogs, there are some cases when it can be a reason for worry. A dog sleeping with eyes open can be a sign of a severe health issue, and when you know something’s off, it would be best to bring your dog to the vet.

Possible Medical Conditions Causing a Dog to Sleep with Eyes Open

1. Narcolepsy

Your dog may be suffering from narcolepsy, a neurological disorder that causes dogs to sleep suddenly, even in the middle of an exercise. It is a condition caused by genetics and is most commonly seen among Doberman Pinschers. It has also been documented in Labradors, Poodles, and Daschunds.

Often, when a dog is in a narcoleptic episode, it sleeps with its eyes open.

2. Seizures

There are two kinds of seizures: grand mal seizures (which cause explosive muscle movements), and petit mal seizures, also known as absence seizures.

The latter doesn’t demonstrate a dramatic event, but your dog could tremble, drool, or lie on the floor with its eyes vacant and unfocused.

You might think your dog is asleep with its eyes open, but in reality, it’s awake and having an absence seizure.

3. Lagophthalmos

This is the medical term used to describe dogs that cannot close their eyes fully. It is usually due to the globe of the eyes being too big for the eyelids, as in the case of dogs with long and flat faces. These dog breeds include Shih Tzus, English bulldogs, and pugs.

However, it can also be caused by an underlying disease such as glaucoma.

Related: Dog breeds with health problems

When to Call the Vet

If your dog is sleeping with its eyes open and you notice the following signs in your dog, you need to call the vet as these are reasons for concern:

  • If you believe your dog is suffering from narcolepsy.
  • If your dog’s eyes seem swollen, itchy, inflamed, or excessively watery.
  • If you can’t rouse your dog by calling its name.

It’s important to note that you should never touch, startle, or shout at a dog that’s sleeping with its eyes open. Remember that this is commonly a survival strategy for dogs, and if they’re startled upon waking, they might mistake it as an act of aggression.


A dog with its eyes partially open when it sleeps is common, as it is with humans. The reasons could be your dog dreaming, it’s the 3rd eyelid you’re seeing, or your dog is in between waking and sleeping.

However, there may be cases wherein it is a sign of a severe condition. If you’re unsure if your dog is simply sleeping or if there’s an underlying medical issue, it’s always best to talk to the vet about it.


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