Have you heard the saying about “sleeping with one eye open”? It’s a bit of metaphoric advice about staying vigilant—and a way to describe very light restless sleep.
But sleeping with eyes open is more than a metaphor. It’s an actual sleep condition—known as nocturnal lagophthalmos—and it is more common than you might think. The National Sleep Foundation estimates that as many as 20% of people sleep with their eyes open. It may sound like just a weird sleep quirk. But nocturnal lagophthalmos can cause problems for both sleep and eye health and is often a sign of an underlying medical condition.
Why do we close our eyes to sleep in the first place?
There are a number of reasons why we close our eyes to sleep. Closed eyelids block light from being absorbed by the eyes, which stimulates the brain to wakefulness. Remember, light is taken in through specialized cells (known as ganglion cells) in the retina. These cells contain the pigment melanopsin, a light-sensitive protein, which transmits information to the brain’s suprachiasmatic nucleus, or SCN. That tiny area is the brain’s hub for controlling circadian rhythms, home to the body’s master bio clock, the regulator of sleep-wake cycles and pretty much all of the body’s processes.
Closing eyes during sleep is also a way the body protects and hydrates the eyes while we rest!
While sleeping, we can’t blink. Blinking is how our eyes stay lubricated, and offers protection from environmental damage, whether too much bright light (think about how often you blink when you move from a dark room to a bright one) or dust and debris in the air. The average frequency of blinking is about 15-20 times a minute. According to this scientific research, blinking may be a kind of micro-meditation. Pretty cool, right?
At night, closed eyes serve as a buffer against stimulation and damage, and keeps the eyes from drying out. Those protections fall away if you’re not actually sleeping with your eyes closed.
Why do people sleep with their eyes open?
With as many as one in five of us unable to fully close our eyes to sleep, nocturnal lagophthalmos is a pretty significant sleep and eye disorder. There are several reasons why you might be sleeping with your eyes open, not closed.
Nerve and muscle problems
Issues with facial nerves and muscles around the eyelid can prevent the lid from closing during sleep. Weakness in facial nerves can happen for several reasons, including:
- Injury and trauma
- Bell’s palsy, a condition that leads to temporary paralysis or weakness in facial muscles
- Autoimmune diseases and infections, including Lyme disease, chickenpox, Guillain-Barre syndrome, mumps, and others
- A rare disorder known as Moebius syndrome, which causes problems with cranial nerves
Damage to the eyelid, including from surgery, injury or illness, can also make it difficult for eyes to close completely during sleep. Among the types of eyelid damage that interfere with eye closure is a condition known as floppy eyelid syndrome, which is associated with obstructive sleep apnea. OSA is linked to several eye disorders, including glaucoma and optic neuropathy, which may cause problems with eyes that can compound sleep problems.
Thyroid-related eye symptoms
Bulging eyes are a common symptom of Graves’ disease, a form of hyperthyroidism, or overactive thyroid. Protruding eyes related to Graves’ disease is a condition known as Graves’ ophthalmopathy, and it can interfere with one’s ability to close eyes while sleeping.
These are the most common reasons for nocturnal lagophthalmos. But it’s also possible to have trouble closing eyes during sleep without an identifiable underlying cause. Whatever the cause, the symptoms of nocturnal lagophthalmos are uncomfortable and the consequences can be problematic, both for sleep and for your eyes. There’s a genetic component to nocturnal lagophthalmos—it tends to run in families.
What happens when you sleep with your eyes open?
When nocturnal lagophthalmos is present, the eye loses the protection of a closed lid and becomes dehydrated and exposed to outside stimuli. This can lead to:
- Eye infection
- Injury, including scratches to the eye
- Corneal damage, including sores or ulcers
Nocturnal lagophthalmos also will interfere directly with sleep. Light filtering through to eyes, eye discomfort and eye dryness all can contribute to restless, poor quality sleep.
One major issue associated with nocturnal lagophthalmos and its treatment? People often don’t know that they have it. Understandably, it can be difficult to tell whether your eyes are closing while you’re sleeping. The symptoms of nocturnal lagophthalmos offer some important clues. Those symptoms include waking with:
- Eyes that feel scratchy, irritated, and dry
- Blurry vision
- Red eyes
- Eye pain
- Eyes that feel tired
Left untreated, nocturnal lagophthalmos can impair your vision, as well as leading to eye infection and cornea damage. It’s important to address these symptoms with your doctor. If you sleep with a partner, you can ask them to check your eyes while you’re sleeping.
How is nocturnal lagophthalmos treated?
Depending on the underlying condition that may be present, and the severity of symptoms, there are several different options for treating nocturnal lagophthalmos.
- Using artificial tears throughout the day helps to create a more robust film of moisture around the eyes, protecting them during the night.
- Eye masks can protect the eyes from damage and stimulation. There are also goggles specifically designed to generate moisture for the eyes while you sleep.
- Using a humidifier also will help you sleep in a moisture-rich environment, in which you’re less likely to dry out your eyes.
- Eyelid weights—which are placed over the outside of the upper eyelid—are sometimes recommended by doctors. Instead of weights, it is sometimes recommended that eyes be taped shut with surgical tape.
- In the most severe cases, surgery becomes a consideration, but most cases don’t require this step.
If you have tired, red, itchy or painful eyes upon waking—or if you think you might have trouble closing your eyes during sleep—talk with your physician. Don’t let your uncomfortable, sleep-related eye symptoms go unaddressed, and you’ll finally get the serious, restful shut-eye you deserve.
Michael J. Breus, Ph.D., DABSM
The Sleep Doctor™