Most dogs that appear to sleep with their eyes open are actually sleeping with their eyelids slightly parted, not fully open. This is normal and surprisingly common. Dogs have a built-in protective layer called the third eyelid (or nictitating membrane) that slides across the eye during rest, keeping it moist and shielded even when the outer lids don’t fully close. So while it may look unsettling, your dog’s eyes are getting more protection than you’d think.
That said, some dogs genuinely can’t close their eyes all the way, and that’s worth understanding because it can sometimes signal a health issue.
The Third Eyelid Does the Heavy Lifting
Dogs have a translucent membrane tucked in the inner corner of each eye. When your dog falls asleep and their outer eyelids relax, this membrane often slides partially or fully across the eye’s surface. It acts like a biological shield, keeping the cornea lubricated and protected from dust or debris. This is why you might see a whitish or pinkish film over your dog’s eye during a nap. It can look strange, but it’s the eye doing exactly what it’s designed to do.
Because of this membrane, a dog sleeping with partially open eyes isn’t experiencing the same dryness or exposure risk that a human would in the same situation. Their eyes have a layer of defense that ours simply don’t.
REM Sleep and Eye Movement
Dogs cycle through the same basic sleep stages as humans, including REM (rapid eye movement) sleep. During REM, your dog’s eyes move beneath their lids, and their eyelids may flutter or crack open slightly. This is also the stage when you’ll see twitching paws, little yips, or paddling legs. All of it is normal dreaming behavior.
These movements are typically brief, lasting less than 30 seconds at a time, and they come and go in bursts. If you watch closely, you’ll notice the partially open eyes tend to coincide with these active dreaming episodes rather than staying open for the entire nap.
Flat-Faced Breeds Are More Prone
Some dogs sleep with their eyes open not because of sleep stages, but because their anatomy makes full eyelid closure physically difficult. This is especially true for brachycephalic (flat-faced) breeds like Shih Tzus, Pugs, Boston Terriers, and French Bulldogs. These breeds have shallow eye sockets and oversized eyelid openings, a combination that leaves more of the eye’s surface exposed at all times.
One study found that 82% of Shih Tzu eyes showed lagophthalmos, which is the clinical term for incomplete eyelid closure. In these dogs, the gap between the upper and lower lids is simply too large for the lids to meet, even during sleep. The protruding eye shape, combined with that oversized opening, means the eyelids can’t fully cover and protect the cornea the way they would in a dog with a longer snout and deeper-set eyes.
If you own a brachycephalic breed, some degree of visible eye during sleep is expected. But it does put these dogs at higher risk for eye surface problems over time, so it’s worth monitoring.
When It Could Signal a Problem
In most cases, sleeping with partially open eyes is harmless. But there are a few situations where it points to something that needs attention.
Facial nerve paralysis can prevent a dog from closing one or both eyes, and it tends to appear suddenly. Dogs with this condition can’t blink on the affected side, and you may notice a drooping ear or lip along with thick, grayish discharge around the eye. This isn’t a sleep quirk. It’s a neurological issue that needs veterinary evaluation.
Chronic dryness is another concern, particularly for breeds already prone to incomplete lid closure. When the eye surface stays exposed for too long without adequate moisture, dogs can develop a condition that causes redness, irritation, a dull or dry look to the eye, and thick yellow-green discharge. Left untreated, this can progress to corneal ulcers, scarring, and even permanent vision loss.
Watch for these specific warning signs:
- Persistent redness or squinting when your dog is awake
- Thick or colored discharge (yellow, green, or gray) around the eyes
- A dull, dry appearance to the eye’s surface
- Dark pigment or visible blood vessels forming on the cornea
- Behavioral changes like reluctance to go outside, hesitation on stairs, or bumping into things, especially at night
Any of these signs, especially in combination, suggest the eye isn’t getting the protection it needs.
Dreaming vs. Something More Serious
Open eyes during sleep sometimes come with twitching, paddling, or vocalizing, and owners occasionally worry they’re watching a seizure rather than a dream. The differences are fairly clear once you know what to look for.
A dreaming dog’s movements are loose and intermittent, usually lasting under 30 seconds. A seizing dog’s limbs tend to be rigid and stiff, with more violent, sustained movement. The simplest test: try gently waking your dog. A dreaming dog will wake up and act normally. A seizing dog typically cannot be roused, and afterward they’re often disoriented, drooling, panting, or may have lost bladder or bowel control.
What You Can Do
For most dogs, no intervention is needed. Their third eyelid handles the job of keeping the eye moist during sleep, and partial eyelid opening during REM cycles is just part of being a dog. If your dog wakes up with clear, comfortable eyes and shows no signs of irritation, there’s nothing to worry about.
For flat-faced breeds or dogs that consistently sleep with a noticeable gap in their eyelids, keep an eye on the condition of the eye surface over time. Making sure your dog’s sleeping area isn’t overly dusty or drafty can help reduce irritation. If you notice any discharge, dryness, or redness developing, a vet can check for early signs of corneal damage and recommend ways to keep the eye lubricated, often with simple eye drops.