Whether it is safe to close your eyes or sleep while wearing contact lenses depends on the lens type and the duration of eye closure. For most contact lenses, the answer is a definitive no, as overnight wear starves the eye of necessary oxygen. Specialized lenses, however, are engineered to safely support limited periods of closed-eye rest. Understanding this difference is important, since wearing any contact lens incorrectly significantly increases the risk of serious eye health complications.
Lens Types and Manufacturer Guidelines
Contact lenses are categorized into Daily Wear (DW) and Extended Wear (EW) or Continuous Wear (CW), which determines safe sleep practices. DW lenses must be removed before any sleep, including short naps. Napping in DW lenses can cause them to dry out and tighten against the cornea, leading to discomfort and complications.
The key difference is the lens material’s ability to transmit oxygen, known as the Dk/t value. Traditional soft lenses have a lower Dk/t value, which is adequate when the eyes are open. When the eyelid closes, the cornea relies solely on oxygen passing through the lens material.
EW and CW lenses use silicone hydrogel, engineered for a significantly higher Dk/t value. This allows more oxygen to pass through the cornea when the eyelids are closed. These lenses are approved for overnight use, sometimes for up to 30 consecutive nights, but only as prescribed. Even with approved lenses, the risk of eye infection remains statistically higher than with daily disposable lenses.
Understanding the Health Consequences
Wearing lenses not approved for overnight use creates an environment primed for harm. The immediate threat is corneal hypoxia (oxygen deprivation), which occurs because the lens blocks the air supply while the eyelid is closed. The cornea responds to this lack of oxygen by swelling, a condition known as corneal edema.
This oxygen-deprived state compromises the cornea’s natural defenses, making it highly susceptible to infection. The closed eyelid prevents the normal flushing action of tears, allowing bacteria and debris trapped beneath the lens to multiply. This combination increases the risk of microbial keratitis, a sight-threatening corneal infection, by six to eightfold compared to not sleeping in lenses.
Microbial keratitis can lead to a corneal ulcer, an open sore on the clear front surface of the eye. Untreated, this condition can cause severe pain, light sensitivity, and permanent vision loss due to scarring. Chronic hypoxia can also trigger neovascularization, the growth of new blood vessels into the cornea, which impairs vision over time.
Responding to Accidental Overnight Wear
If you wake up having accidentally slept in your lenses, avoid immediate, forceful removal of a dry, adhered lens. Attempting to pinch or pull a stuck lens can cause an abrasion or tear on the corneal surface. The first action should be to hydrate the eye and the lens.
Hydrating the Lens
Apply several drops of sterile saline or contact lens rewetting drops to the affected eye. Do not use tap water or standard disinfecting solution, as they are not formulated for eye lubrication. Close your eye and wait several minutes to allow the lens to reabsorb moisture and regain flexibility.
Removal and Recovery
Once the lens moves freely, attempt gentle removal. Discard daily disposable lenses immediately. Reusable lenses must be thoroughly cleaned and disinfected before storing, but do not reinsert them right away.
Give your eyes a rest period of at least 24 hours to recover. If you experience persistent redness, pain, increased light sensitivity, or blurred vision after removal, contact an eye care professional immediately.