Why do dogs sleep with their eyes open?
If you've ever spotted your dog mid-slumber, you might notice that they occasionally appear to sleep with their eyes partly open, rolled back, and unfocused. As strange as this may seem, it is common and usually normal.
It's thought that his behavior can be primarily attributed to canine sleep patterns. While some pup parents may find this disconcerting, it's generally considered normal and doesn't necessarily indicate any health issues.
While there is no precise scientific explanation for why dogs sleep with their eyes open, there are a few theories that touch on behavioral and physiological causes:
Behavioral Reasons Dogs Sleep With Their Eyes Open
Partial Wakefulness
The most likely explanation is that your dog may not be fully asleep. When they are in the early stages of sleep, dogs are deeply relaxed but are still lightly dozing. So, they might appear asleep in this state but they have not fully lost consciousness yet, so their eyes won't be fully closed.
These dogs usually become fully aware again very quickly with only minimal stimulation or disturbance (for example, if another animal or pet walks by or you call their name quietly or pat their head).
Alertness & Self-Protective Instincts
Another theory about why dogs look like they're sleeping with their eyes open is related to evolution. All wild animals, including dogs, must remain somewhat situationally aware so they can be ready to protect themselves from predators or hazards that may infringe on their territory.
While your pup is likely safe in your home, they may have retained some of their early protective instinct. Even as they near deep sleep, part of their brain may still be alert and functioning.
Breed-Specific Traits
The physical characteristics of some dog breeds make them more likely to sleep with their eyes at least partially open. For example, pugs, bulldogs, and other brachycephalic breeds have shorter snouts and a more prominent forehead, which can cause their eyes to appear to bulge slightly. This can make it look like their eyes are open even when they are closed.
Additionally, dogs with large eyes that protrude form their face, like chihuahuas and Pekingese, may also sleep with their eyes open.
Third Eyelid Function
Some dogs have a raised third eyelid (also referred to as a nictitating membrane) that shows while they are asleep. The membrane is a partly clear, protective layer that covers the eye. It typically appears from the corner of the eye nearest the nose, and often as a yellow or pink hue.
This can make it appear as if your pup is sleeping with their eyes open, but the third eyelid remains closed the entire time they are napping. As such, your pooch does not risk exposure to dry eye syndrome (also referred to as keratopathy).
Physiological Reasons Dogs Sleep With Their Eyes Open
Being in the REM Phase of Sleep
Dogs have a different sleep structure than humans. Instead of sleeping for seven to nine hours at a stretch, they sleep on and off throughout the day. However, they also enjoy both REM and non-REM sleep cycles. Each wake-sleep cycle for dogs is 83 minutes long. During this time, they spend significant time in REM sleep (dreaming stage).
Many dogs slumber with their eyes partly open, which can make them appear awake during this phase. If your dog is dreaming, you may see them bark or twitch. Their eyes may move or flicker as they visualize chasing their siblings, or other animals around your backyard or park.
If you've ever wondered, "Why does my dog sleep with his eyes half open?", this may be the reason.
Dogs in this stage of sleep may appear to be having a seizure because they are unconscious but still displaying eye movement, and sometimes vocalizing. However, dogs that are experiencing a seizure often experience more violent movements and are impossible to arouse. Their eyes will also often be fully open and appear to be staring into space, as opposed to dogs' relaxed, half-open eyes when they are in mid-nap.
Aging
If you've ever asked yourself, "Why does my older dog sleep with his eyes open?", his age may be at least a partial explanation. As dogs age and enter their golden years, they may experience changes in their sleeping habits and patterns. This can include sleeping with their eyes partially open. However, it's more common for younger, energetic dogs to sleep with their eyes partly open.
Potential Health Concerns
While your dog's open-eyed slumbers may be nothing to worry about, they can also be a sign of potential eye conditions or health issues, like:
Abnormal Eye Movement
If your dog's eyes are moving quickly or twitching and seizing while he is sleeping, this can indicate a neurological disorder or other health issue. Consult your veterinarian or veterinary ophthalmologist to rule out any underlying conditions.
Eye Infections
Eye infections like conjunctivitis (inflammation of the conjunctiva) can cause dogs to keep their eyes open while they sleep. Fungi, bacteria, or viruses can cause these infections and lead to swelling, redness, discharge, and pain or discomfort. Left untreated, eye infections can lead to more serious eye problems, including dry eye, long-term damage and vision loss.
Eye Abnormalities
Certain Eye abnormalities like ectropion or eyelid agenesis can affect a dog's ability to close their eyes. Dogs with these conditions may sleep with their eyes open to protect their eyes from drying out.
Eyelid agenesis is a congenital condition that causes a dog to be born without one or both eyelids. Ectropion is a condition in which the eyelid droops outward, exposing the eyelid's inner surface.
Eye Trauma
If your dog has experienced an eye injury, it may sleep with its eyes open to protect the injured eye. Signs of eye trauma include redness, swelling, cloudiness, and discharge.
Should I be concerned if my dog sleeps with his eyes open?
There are some instances in which you should be concerned about your dog sleeping with his eyes open and contact your vet right away to book an exam. These include:
- Your dog seems lost or disoriented, is not acting like his normal self, or is falling over when they wake up. This can be a sign of a seizure.
- You notice irritation, redness, or discharge from your dog's eyes.
- Your dog is falling asleep at odd times of the day, or in unusual places.
- Your dog seems restless, physically uncomfortable, or in pain.
If you notice that your dog has suddenly started sleeping with his eyes open, have seen other unusual behaviors, or are concerned about your dog's sleep pattern, you may want to record a video and consult with your vet or ask for a referral to our veterinary eye specialists, as having a visual example of exactly what's happening can help a veterinarian accurately diagnose the issue.
Our veterinary eye specialists at Northwest Animal Eye Specialists are equipped to perform an eye exam, diagnose a variety of eye conditions or issues, and provide treatment and advice specific to your dog's needs.
Note: Northwest Animal Eye Specialists specializes in treating eye conditions and illnesses. The advice provided in this post is intended for informational purposes and does not constitute medical or behavioral advice regarding pets. Please make an appointment with your vet for an accurate diagnosis of your pet's condition.