The question of how long to close your eyes while wearing contact lenses often arises from the common situation of dozing off or taking an accidental nap. While closing your eyes for a few seconds to rest them is harmless, any extended closure, such as sleeping, introduces significant risks to the health of your eyes. Understanding the physical mechanisms at play, particularly the need for oxygen, helps explain why eye care professionals strongly caution against this practice.
The Critical Role of Corneal Oxygenation
The cornea, the clear, dome-shaped front surface of the eye, receives its oxygen directly from the air rather than from blood vessels, a process occurring through the tear film when the eye is open. A contact lens acts as a physical barrier, naturally reducing the amount of oxygen reaching the corneal surface, even during waking hours.
Closing the eyelids further compounds this issue by cutting off the primary source of atmospheric oxygen. When the eyes are shut, the cornea must rely on the limited oxygen supplied by the blood vessels at the edge of the cornea and the aqueous humor. This lack of oxygen is scientifically termed corneal hypoxia.
Prolonged hypoxia triggers a defensive reaction in the eye, leading to several complications. One immediate effect is corneal edema, where the cornea swells because it cannot properly regulate its fluid balance. Chronic oxygen deprivation can cause blood vessels to grow into the cornea, a condition called neovascularization, which clouds vision. This oxygen-starved environment also creates a perfect breeding ground for bacteria, significantly elevating the risk of serious infections like microbial keratitis.
Official Guidelines for Sleeping and Napping
For most contact lens users, the official guideline is straightforward: standard soft contact lenses should never be worn while sleeping, regardless of the duration. This rule applies equally to an eight-hour night of sleep and a short 30-minute nap. Even a brief nap exponentially increases the risk of a contact lens-related infection compared to wearing the lenses while awake.
Accidentally sleeping in lenses increases the risk of eye infection by six to eight times, with some studies suggesting a tenfold increase. The risk is not solely tied to the lens material blocking oxygen. The closed eyelid traps bacteria and other microorganisms against the eye’s surface, where they can multiply rapidly in the warm, moist environment.
The only truly safe duration for closing the eyes with contacts is the time it takes to blink or rest the eyes momentarily, which is a few seconds. If you feel the need to close your eyes for more than a brief rest, the safest action is always to remove the lenses first. Avoiding closed-eye oxygen deprivation, even for a short nap, is necessary to preserve long-term corneal health.
Understanding Extended-Wear and Daily Disposables
The primary exception to the strict no-sleeping rule involves specific types of lenses known as extended-wear contacts. These lenses are engineered using highly breathable materials, often silicone hydrogel, which possess a much higher oxygen permeability (Dk/t value). This specialized design allows a greater amount of oxygen to pass through the lens to the cornea, making them approved for continuous wear for up to seven or even 30 days.
However, even with this advanced technology, never assume your lenses are approved for overnight wear unless explicitly instructed by your eye care professional. The high oxygen transmission of extended-wear lenses only makes overnight wear possible, not risk-free. The risk of developing an infection remains higher with extended-wear lenses than with daily-wear lenses that are removed every night.
Daily disposable and conventional soft contact lenses, which are only approved for daily wear, should always be removed before any period of sleep. These standard lenses do not provide the necessary oxygen flow to safely sustain the cornea during the closed-eye state. Removing lenses nightly allows the cornea a full period of rest and maximum oxygen exposure, which is the gold standard for maintaining healthy eyes.
Immediate Steps After Waking Up With Contacts
If you wake up and realize you have accidentally slept in your lenses, resist the urge to immediately pinch or pull them out. After extended eye closure, the lenses are likely dehydrated and may be suctioned tightly to the cornea’s surface. Forcing a dry lens off the eye can cause a painful corneal abrasion, peeling away the delicate surface layer.
The immediate step is to rehydrate the eyes and the lenses. Apply a few drops of sterile rewetting drops or preservative-free saline solution to your eyes and blink gently. This fluid needs a minimum of 5 to 10 minutes to work its way under the lens, lubricating it and allowing the cornea to rehydrate slightly.
Once the lens is visibly moving freely and no longer feels stuck, wash your hands and gently remove it. Discard the compromised lenses and switch to glasses for the rest of the day, allowing the corneas 24 hours to recover and reoxygenate. If symptoms like persistent pain, blurred vision, or severe light sensitivity continue for more than a few hours, contact an eye care professional immediately, as these are signs of a more serious complication.