If dogs sleep with their eyes open, it is usually due to their nictitating membrane, their guarding instinct or their breed. Under certain circumstances, sleep apnea, epilepsy, sleep disorders or dreams can also be responsible.
According to studies, around 20% of all people sleep with their eyes open. However, it is more common in dogs as they need an average of around 60% more sleep. [1]
As a rule, this is not a reason to worry. Illnesses are only the trigger here in rare, exceptional cases. Below you will learn about the 9 most common causes.
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#1 nictitating membrane
The nictitating membrane is like a kind of “third eyelid” that is present in many vertebrates such as dogs, cats, cows, bears, birds and many rodents.
You can think of them as a kind of additional protective goggles. People also have a nictitating membrane. But for us it is far too short to cover the entire eye.
This explains why it often appears as if dogs sleep with their eyes open. In reality, the eyeball is covered by the whitish nictitating membrane.
If this were not the case, the eye would dry out within a very short time and corneal inflammation would occur. [2]
nictitating membranes in dogs and birds
In dogs, this layer primarily protects against mechanical influences such as scratches. It also offers protection against dust particles and drying out of the eyes.
Seals also use them as a type of swimming goggles when diving. In polar bears, the nictitating membrane acts as a kind of snow goggles and protects against snow blindness. [3]
Unlike some birds, dogs cannot consciously control the nictitating membrane. It therefore automatically pulls to the side as soon as the dog wakes up.
Dogs often have their front eyelids open while sleeping, but protect their eyes with the whitish and transparent nictitating membrane. This makes it appear as if the dog is actually sleeping with his eyes open. This is not possible with humans.
#2 REM behavior disorder
Dogs have the same sleep phases as humans. Dreams take place particularly in the REM phase (“Rapid Eye Movement”).
Dogs primarily process their everyday experiences. These dreams are often so vivid and vivid that you can see it in their body:
- Soft barking in sleep
- Moving eyelids
- Muscle twitches [4]
Basically, dreams for dogs are a good sign. Because they signal that the four-legged friend is doing well physically and mentally.
In exceptional cases, a so-called “REM behavior disorder” can also occur, in which the dog endangers both itself and those present.
Affected dogs have such vivid nightmares that they begin to growl, bark, run or even bite in their sleep. Their eyes are also usually open while they sleep.
In many cases, such a behavioral disorder is accompanied by severe stress and anxiety. Because of panic, dogs often injure themselves or even attack their owners. [5]
If you suspect this, you should visit the vet here. This can not only examine your dog in the sleep laboratory, but also regulate sleep activity with medication.
With REM behavior disorder, dogs experience such intense dreams that they hallucinate and overreact. They often appear completely awake, have their eyes open in their sleep and even walk around the apartment.
#3 Guardian and guard instinct
Many guard dogs and sheepdogs often sleep with their eyes half-open, so that a small slit always remains open. This is a breed-specific instinct.
In the past, guard dogs could hardly afford to switch off completely in the wild, both for their own protection and that of their master.
However, if they sleep with their eyes half-open, it usually gives the impression to other predators that they are awake. And that in turn can prevent an attack.
In addition, dogs' sleep cycle is only 20 minutes. In humans, a cycle lasts a full 90 minutes – around 5 times longer. [6]
Dogs therefore naturally wake up in their sleep significantly more often than we do. This allows them to check their surroundings much more regularly for potential dangers.
Shepherd's eyes and guard instinct
You've probably noticed that some German Shepherds have lighter patches of fur on the inside of their eyebrows. These are so-called “shepherd’s eyes”.
Because from a distance, even with his eyes closed, it looks as if the dog is always keeping an eye on his herd. The nictitating membrane can take on the same function here.
Because when dogs sleep with their eyes open, it looks as if they have an eye on the herd around the clock. So running away is not an option.
These breeds are also colloquially known as “Vieräugl”.
In sheepdogs and guard dogs, the guarding and guarding instinct is sometimes so strong that they express themselves even at night. Here, sleeping with eyes open is a survival and protective mechanism that is anchored in their genes due to their past.
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#4 Seizures
Among other things, an epileptic seizure while sleeping can cause the dog's eyes to be wide open. These attacks are caused by nerve disease.
In most cases, you can tell if your dog looks very rigidly and his eyelids twitch slightly. Other typical symptoms are:
- Tense posture
- Dog falls over
- Strong tremors
- Dog is unresponsive
- Drooling and foam in the mouth [7]
If such an attack occurs while sleeping, you can usually tell if the dog's eyes are wide open and hardly move.
According to studies, around 1% of all dogs struggle with epilepsy. Male dogs and young puppies are most commonly affected. [8]
In addition to poisoning, anemia and brain injuries, strokes, brain tumors or even liver and kidney failure can also be responsible.
Although such attacks are usually painless, they can lead to permanent damage. If you suspect this, you should go to the vet for diagnosis and treatment.
Epileptic dogs occasionally have seizures while sleeping. What is noticeable here is that the eyes are suddenly wide open during sleep, the pupils hardly move and the dog does not respond to commands. The vet can help here.
#5 Lagophthalmos
When dogs naturally cannot close their eyelids completely, this is called “lagophthalmos”. This phenomenon is also known as “rabbit eye”.
Dog breeds with a short nose and large googly eyes are primarily affected. Typical examples of these are:
- pug
- boxer
- Boston terriers
- Bulldog
- Pekingese
- Shih Tzu [9]
In the past, these breeds were bred so heavily that they are now classified as “torture breeding” and animal welfare strictly regulates breeding.
Cruel breeding is when pain and behavioral disorders of animals are tolerated just to achieve certain characteristics in the animal.
Lagophthalmos is also one of them. This disorder not only causes dogs to sleep with their eyes open at night, but also causes the eye to dry out. [10]
The above breeds therefore have to deal with eye infections at an above-average rate. In addition, the eyes are much less protected from scratches, water and sun.
Here you should visit the vet. In some cases, eye drops can be enough for treatment. In some cases the eyelid is also surgically corrected.
Dogs with a flat muzzle often struggle with lagophthalmos, which prevents them from closing their eyelids completely. When you sleep, it usually looks as if you are sleeping with your eyes open. The veterinarian should be consulted for treatment.
#6 Sleep apnea
Sleep apnea occurs when you unconsciously stop breathing during sleep. As a result, the dog's brain regularly lacks oxygen, causing him to wake up.
In principle, any dog can suffer from sleep apnea. However, overweight dogs and four-legged friends with a short snout are statistically most often affected.
For example, English bulldogs, Boston terriers, pugs and a large number of all Great Dane species. The most common symptoms here include:
- Loud snoring
- Irritability during the day
- Sleeping with your eyes open
- Excessive daytime tiredness
- Restless sleep [11]
If sleep apnea is caused by being overweight, a diet is usually enough to improve it. Because here the fatty tissue blocks the airways.
If the cause is allergies, an allergy test is usually carried out. In the case of breed-specific problems, surgery may sometimes be necessary.
Dogs with sleep apnea experience regular pauses in breathing while sleeping, which causes them to wake up significantly more often. Among other things, these dogs also tend to snore very loudly and sleep with their eyes open. If you suspect this, you should consult your veterinarian.
#7 Prolapse of the nictitating gland
When the nictitating gland prolapse occurs, a reddish blister forms on the inside of the eye. Because it has a rounded shape, it is also known as “cherry eye”.
This is the so-called nictitating gland, which normally produces around 40% of the eye fluid. However, under certain circumstances this can also come out.
In this case, it causes the dog to have poorer vision and always have his eyes slightly open both during the day and while sleeping. This in turn leads to dehydration.
Here too, those breeds with a short snout are more often affected due to genetic reasons. This includes:
- Bulldogs
- cocker spaniel
- Shih Tzus
- Boston terriers
- Pug [12]
You should visit the vet here for treatment. In some cases it is enough to correct the gland with massages and antibiotics.
In other cases, surgery may also be necessary. This is especially true if the gland is so large that your dog can no longer close his eyes. [13]
When the nictitating gland prolapse occurs, the eye gland becomes detached and inflates. This red vault is particularly noticeable in short-snouted dogs. In extreme cases, it also means that the four-legged friends always have their eyes slightly open, even when they are sleeping.
#8 Narcolepsy
Narcolepsy is a disorder of the nervous system that causes dogs to suddenly fall over and fall asleep at even the most inopportune moments.
Typically, the four-legged friends wake up again a short time later and behave as if nothing was happening…