Watching our pups sleep can be very peaceful, and may make you feel like taking a nap as well. However, if you’re watching your dog snooze, you may notice something interesting. Your dog may not actually have their eyes fully closed while they are sleeping.
It is quite common for dogs to have their eyes open or at least partially open every time they sleep or for part of the time that they are sleeping. You may find yourself wondering, why exactly do dogs sleep with their eyes open?
Normal reasons for dogs to sleep with their eyes open
Dogs have a third eyelid
Dogs have an extra eyelid, known as the nictitating membrane. People also have something like a nictitating membrane, but for humans, this membrane is no longer evolutionarily essential, so it has reduced to a small bump in the inner corner of the eye for people.
An essential purpose of this membrane is to clear debris away from the eye. One of the reasons that people don’t have evident nictitating membranes like dogs do is because we have hands to wipe away debris, so the function of the membrane is much less important for us.
For dogs, who don’t have hands to wipe away debris and whose faces are near the ground where it is easy for dust and debris to get into the eyes, this membrane is essential to keep their eyes healthy and protect them from injury.
This membrane is completely passive, which means that your dog can’t control it. It doesn’t have any muscles or other ways for your dog to move it. The membrane comes across the eyeball when the other eyelids are closed and the eyeball has rolled back.
When the dog wakes up, it recedes back into the inner corner of the eye again. For various reasons, the primary lid may not be closed all the way while your dog is sleeping, but this membrane may be active. Since the membrane is clear, we may not be able to tell that it is there, making it appear that the dog’s eye is simply open.
Dogs may open their eyes while dreaming
When dogs dream, they have small movements and twitches, and sometimes their eyes also twitch open or remain open while they are dreaming. One theory is that dogs keep their eyes a little bit open when they are in a deep sleep state and in the midst of dreams.
Being in a deep sleep state would have made dogs vulnerable in the wild, so having the eyes slightly open may be a way for dogs to be aware of potential danger while they are still sleeping. It may be that as dogs have become domesticated and no longer in danger during deep sleep, the tendency becomes less likely.
Regardless of the reason, it does seem that dogs are more likely to have their eyes open while they are dreaming than during lighter sleep phases.
Abnormal reasons for dogs to have their eyes open while sleeping
Dogs who are experiencing a seizure while they sleep may have their eyes open or open and close their eyes. Seizures can vary from causing only very slight twitches and movements to movements that convulse the entire body. It can be difficult to tell whether your dog is having a seizure or simply dreaming, especially if the seizure activity is quite light.
There are a few key differences between a dog who is sleeping and a dog who is seizing that can help you determine what is going on with your dog:
- Sleeping dogs usually only open their eyes a small amount. It is very normal for a sleeping dog to have a slit of eye visible, but dogs who are having a seizure are more likely to open their eyes widely, and the eyes may also be rolling around in the head.
- Sleeping dogs have a relaxed expression. It is normal for a dog to show a variety of facial expressions while they are dreaming, and they may even open and close their mouths, but you can expect to see much more dramatic jaw movements and an expression that is not relaxed when a dog is having a seizure. The jaw may snap open and closed and a dog may even bite his own tongue during a seizure.
- Sleeping dogs will have muted vocalizations. Many dogs whimper, yelp, or bark in their sleep, but the degree of the sound will be muted by paralysis during sleep. It will sound as though the noises that the dog is making are muted or muffled. On the other hand, a dog who is experiencing a seizure may make fully vocalized sounds of distress like moaning, whining, or crying.
- Sleeping dogs are responsive. It can be difficult to wake up a dog who is deeply asleep, but with a little bit of shaking or calling their name loudly, you can wake the dog up. By contrast, a dog who is experiencing seizures will not respond to you no matter how much you call their name or shake them.
If your dog is seizing
Here is what you can do to protect yourself and make your dog as comfortable as possible until the seizure is over and what to do right after the seizure.
- Stay calm. Your dog will likely be feeling very panicky when they come out of a seizure, so it is essential that you maintain a calm state of mind throughout the seizure and afterward. Being calm and confident will help your dog to feel calmer and make it less likely that they will have a bad reaction to you after the seizure.
- Remove dangers from around your dog. Your dog cannot control their body while they are seizing, so they may fall off of a couch or hit their head on objects around them such as a coffee table. It can be dangerous to move your dog while they are seizing, but do your best to make sure that they are not going to roll off of the surface they are on and clear obstacles from around them so they won’t hurt themselves.
- Protect yourself and your family. Most dogs come out of a seizure feeling disoriented, confused, sick, and exhausted. A small percentage of dogs may show aggression as they come out of a seizure. Sometimes this aggression may be very intense and dogs may actively seek out and attack you, your family members, or other pets in the household. Sometimes other pets will attack a seizing dog since they do not understand this behavior and find it threatening. No matter how good your dog’s relationship is with other members of the family, this is not relevant during behavior caused by a seizure. Protect your family by keeping everybody away from your dog until they have come out of the seizure fully.
- Go to the vet. Medication can reduce or prevent seizures, so go to the vet as soon as you know that your dog is suffering from seizures. It is important to seek out medical care as soon as possible since seizures can get worse over time.
Some dogs have trouble closing their eyes all the way
Some breeds of dogs are less able to close their eyelids than other dogs. This is especially common in dogs who tend to have very large, rounded eyes. These kinds of eyes tend to go along with the short snout known as brachycephalic.
Brachycephalic dog breeds who may be prone to having eyelids that don’t close all the way include Boston Terriers, French and English Bulldogs, Pugs, Shih Tzus, and Pekingese. The condition by which dogs cannot close their eyelids fully is known as Lagophthalmia.
You are unlikely to notice that your dog can’t close their eyes fully when they are awake, but when your dog is sleeping it will become clear that they are not closing their eyes all the way. Lagophthalmia can result in other problems with the eye such as chronic dry eye and repeated irritation of the eye since dogs can’t close their eyelids completely in order to prevent debris from coming into the eye.
Let your veterinarian know as soon as you realize that your dog can’t close their eyes fully. Your veterinarian will most likely prescribe a daily tear substitute, also known as eye lubricants, to help clear debris from the eye and keep it moist.