Surprisingly, nighttime can be a potentially damaging time for those suffering from dry eye disease. Even though our eyes are closed, the front surface of our eye is not necessarily protected. Some underlying conditions can cause extreme dryness overnight that may worsen dry eye disease, leaving the eyes feeling gritty, burning, and uncomfortable in the morning. Understanding the potential causes of nighttime dryness can reduce the risk of discomfort and irritation, and may help protect the ocular surface. Read on to learn more about causes of nighttime dryness and how to address them.
What is Nocturnal Lagophthalmos?
Nocturnal lagophthalmos is the most common cause of overnight dryness. This condition occurs during sleep when the eyelids do not fully close or open slightly throughout the night. This results in a portion of the cornea being exposed for extended periods of time, without the eyelid or the tear film properly protecting it. In these cases, the outermost layer of the cornea usually becomes damaged and disrupted, which results in symptoms of dryness such as burning, irritation, and light sensitivity. Based on the severity of the eyelid problem, nocturnal lagophthalmos can result in a varying amount of exposure of the cornea, from a millimeter to a majority of the ocular surface.
Your eye doctor can diagnose nocturnal lagophthalmos during a routine eye exam based on symptoms and a distinct pattern of corneal damage. If your doctor suspects you are suffering from this cause of nighttime dryness, they may suggest a series of treatment options, including overnight eye drops or ointments that work to protect the front surface of the eye overnight. These treatment approaches, in addition to other options such as an eye mask, can be used to reduce damage to the cornea due to exposure, and minimize symptoms of dryness in the morning.
Sleep Apnea and Dry Eyes at Nighttime
Sleep apnea is a condition that causes difficulty breathing during sleep. In addition to breathing problems, sleep apnea is associated with an increased risk for dry eye symptoms for several different reasons. Those with sleep apnea are frequently prescribed a Continuous Positive Airway Pressure (CPAP) machine. A CPAP mask rests over the nose and mouth and administers a constant flow of air to prevent breathing problems during sleep; however, if the mask is loose or does not fit properly, it can result in a constant airstream bombarding the ocular surface, and can dramatically worsen symptoms such as burning and irritation. Beyond the risks of nighttime dryness associated with a CPAP machine, sleep apnea is associated with a condition known as Floppy Eyelid Syndrome, which also worsen symptoms of dry eye disease. As the name suggests, Floppy Eyelid Syndrome results in eyelids that are loose and may have the tendency to flip over, especially during sleep when they are in close contact with a pillow. If the eyelids are unknowingly flipped overnight, the front of the eye can be exposed and corneal damage can occur. Whether it is due to a CPAP machine or Floppy Eyelid Syndrome, nighttime dryness due to sleep apnea can be addressed through methods such as eye drops or ointments.