The simple answer for the vast majority of standard contact lenses is no, you should not sleep in them. Contact lenses are medical devices designed to sit on the clear front surface of the eye, known as the cornea, to correct vision. Wearing them while asleep dramatically increases the risk of serious health complications. This is true even for short naps, as any period of sleep prevents the eye from accessing the necessary elements to maintain its health.
The Physiology of Overnight Contact Wear
The cornea contains no blood vessels, relying instead on oxygen absorbed directly from the air. A contact lens partially restricts this process during the day. When the eyes are open, tears and the atmosphere provide a continuous supply of oxygen to the cornea.
When the eyelids close during sleep, the oxygen supply is naturally reduced because the cornea must now rely on the oxygen available in the blood vessels of the inner eyelid. Introducing a contact lens creates a further barrier, which significantly decreases the amount of oxygen reaching the corneal tissue. This condition is known as corneal hypoxia, which can cause the cornea to swell slightly and impairs its natural ability to fight off bacteria and flush away debris.
Potential Risks and Complications
The physiological stress of reduced oxygen and moisture creates a vulnerable environment, leading to a much higher risk of infection and damage. Studies indicate that sleeping in contacts increases the risk of a serious eye infection by six to eight times compared to removing them nightly. The most severe consequence is microbial keratitis, which is a painful infection of the cornea.
Microbial keratitis can be caused by various pathogens, including bacteria like Pseudomonas aeruginosa, which thrive in the warm, low-oxygen conditions beneath a lens. This infection can quickly lead to a corneal ulcer, which is an open sore on the clear surface of the eye. Untreated or severe ulcers can result in permanent scarring of the cornea and potentially vision loss, sometimes requiring a corneal transplant to correct. Chronic oxygen deprivation can also trigger neovascularization, which involves the growth of new, abnormal blood vessels into the clear cornea, potentially obstructing vision.
Understanding Extended Wear Lenses
Extended wear (EW) lenses are approved by the FDA for continuous wear for a set period, typically ranging from six nights to 30 days. These lenses are made from advanced materials, primarily silicone hydrogel, which is designed to allow a much higher level of oxygen permeability to the cornea. The silicone component dramatically increases the oxygen transmission, making them safer for occasional or prescribed overnight use than standard hydrogel lenses.
However, the term “extended wear” does not mean “risk-free,” and the overall risk of microbial keratitis remains elevated compared to daily-wear lenses. Eye care professionals often recommend limiting overnight wear even with these specialized lenses. Anyone considering extended wear must use them strictly according to their eye doctor’s prescribed schedule, which includes mandatory removal and cleaning periods. Professional supervision is necessary to monitor for early signs of complications.
What to Do If You Accidentally Sleep in Contacts
If you wake up having unintentionally slept in your lenses, the first and most important step is to resist the immediate urge to pull them out. The lens is likely dry and suctioned tightly to the cornea, and forcing removal can cause a painful corneal abrasion. Instead, you must first rehydrate the eye.
Apply a few drops of sterile saline solution or contact lens rewetting drops liberally to the eye while the lens is still in place. You should then wait 15 to 30 minutes, allowing the lens to rehydrate and loosen from the cornea. Once the lens can move freely on your eye, wash your hands thoroughly and remove it gently. After removing the lenses, discard them immediately, as they have trapped significant amounts of debris and bacteria. Switch to wearing glasses for at least a full day to let your corneas fully recover, and seek medical attention if you experience persistent redness, pain, blurred vision, or sensitivity to light.