Sleeping with eyes partially or fully open is an uncommon physiological phenomenon. This behavior is considered an abnormality in the coordinated muscle relaxation that characterizes healthy sleep. Understanding this involves looking at the underlying biological mechanisms that control eyelid closure during rest.
The Medical Definition of Sleeping With Open Eyes
The medical community refers to the inability to fully close the eyelids during sleep as Nocturnal Lagophthalmos. This condition is defined by the degree of palpebral fissure exposure that remains when a person is asleep.
The root cause lies in the failure of the orbicularis oculi muscle to contract completely. This circular muscle surrounds the eye and is solely responsible for eyelid closure. When Nocturnal Lagophthalmos occurs, the muscle either does not receive the proper neural signal or is physically compromised, resulting in incomplete eye coverage.
The severity ranges from a barely noticeable gap to complete exposure of the entire ocular surface. Even mild cases, where the lower portion of the cornea remains exposed, can lead to complications over time. The condition is labeled “nocturnal” to distinguish it from the inability to close the eye while awake, which often signals acute facial nerve issues.
Identifying the Underlying Causes
The etiology of Nocturnal Lagophthalmos is highly varied, often categorized into neurological, anatomical, and infectious origins.
Neurological Factors
Neurological factors frequently involve damage to the seventh cranial nerve (the facial nerve), which innervates the orbicularis oculi muscle. Conditions like Bell’s palsy, a sudden, temporary weakness in the facial muscles, are a common cause of acute lagophthalmos due to impaired nerve function.
Anatomical Factors
Physical and anatomical factors can prevent complete lid closure, even when the nerve and muscle are functioning correctly. Individuals with prominent eyeballs (proptosis) may find their lids are too short to cover the entire globe. Previous cosmetic surgeries, particularly aggressive blepharoplasty, can inadvertently lead to shortening of the eyelid, altering the natural lid structure and causing exposure.
Infectious and Congenital Factors
Infectious causes stem from diseases that directly damage the facial nerve or the eyelid tissue itself. For example, the herpes zoster virus (shingles) can target the facial nerve and lead to temporary or permanent paralysis of the eyelid muscles. Genetic or congenital factors are also implicated in some cases, where the eyelid structure or muscle function is inherently underdeveloped or compromised from birth.
Risks of Ocular Exposure During Sleep
The primary danger of sleeping with open eyes is the prolonged exposure of the ocular surface to the air, which disrupts the natural tear film. The tear film lubricates and protects the cornea and conjunctiva, relying on blinking for constant replenishment. When the eye is exposed during sleep, the tear film rapidly evaporates, leading to intense dryness and irritation.
This chronic dryness can quickly progress to a more serious condition known as Exposure Keratopathy. Keratopathy refers to damage to the corneal surface, characterized by superficial drying, breakdown of epithelial cells, and inflammation. The areas of the cornea that are exposed first, typically the lower third, are the most susceptible to this cellular damage.
The lack of complete lid closure eliminates the physical barrier that protects the eye from airborne irritants and debris. The natural flushing and cleaning action of the full blink is absent, which significantly increases the risk of eye infections. Pathogens can adhere to the dry, compromised corneal surface and potentially lead to corneal ulcers, which are painful and severely impact vision. Immediate consultation with an eye care professional is warranted if a person experiences severe pain, persistent redness, or any noticeable change in visual acuity.
Managing and Treating the Condition
Management of Nocturnal Lagophthalmos focuses on restoring and maintaining the moisture of the exposed ocular surface. Non-surgical interventions are the first line of defense, often involving the liberal use of artificial tear drops, gels, and thick lubricating ointments applied just before bedtime. These viscous preparations are designed to resist evaporation throughout the night.
Moisture shields or specialized sleep goggles can create a humid microenvironment around the eyes, minimizing tear evaporation. In persistent cases, a doctor may recommend the temporary application of medical-grade surgical tape to gently hold the upper and lower eyelids closed overnight.
For severe, persistent cases that do not respond to conservative measures, surgical options may be explored to improve lid function. Procedures such as a tarsorrhaphy involve temporarily or permanently joining parts of the upper and lower eyelids to narrow the opening, effectively reducing the exposed surface area. Other surgeries focus on implanting a small gold or platinum weight into the upper eyelid to assist gravity in achieving complete closure.