If you’ve been sleeping while wearing your contact lenses, you may want to think about changing your bedtime routine. Here are some of the reasons why leaving your contact lenses in while you sleep is a bad idea:

1. Like any other part of your body, your cornea needs oxygen. So how does that happen during the day while you’re wearing contacts? It’s all due to blinking when considering hard or rigid lenses. Every time you blink, the contact lens moves, allowing oxygen carrying tears to travel under the lens allowing oxygen diffusion into the cornea. With soft lenses, tears containing oxygen are carried thru the lens material and into the cornea. Not all soft lenses are created equal. Silicone hydrogel lenses allow more oxygen transmission thru the lens material. The higher the oxygen transmission the better. Older materials, such as hydrogel lenses, that contain no silicone, do not allow as much oxygen transmission. However, while you sleep and the eyes are obviously closed, much less oxygen gets to the eye. This causes some overnight corneal swelling that a normal, healthy eye can clear easily within an hour of waking. When you sleep wearing contact lenses, even less oxygen gets to the corneal surface as the contact lens acts as a physical barrier to the flow of oxygen.
2. When you remove your contact lenses before bedtime, you improve oxygen flow to the eye and reduce the chances of infection. In the case that your eye’s skin (i.e. the epithelium) is compromised, it provides an open invitation to pathogens (i.e. bacteria, fungus, etc.) to take up residence within the cornea. To reduce the chances of infection, take your contacts out before bed, make sure that you’re soaking them in the appropriate solution, and change them as per the manufacturer’s or optometrist’s directions. The aforementioned compromised epithelium shows up during the course of a slit lamp observation using fluorescein dye staining.
3. Contact lenses, even worn for shorter periods of time, can cause dryness and redness. Use eye lubricants when needed, and never wear contact lenses when the eye appears red. Having an up to date pair of prescription glasses as a back up to contact lens wear is paramount.
4. An ophthalmology study showed that the chances of developing keratitis (which is an infection or inflammation of your cornea) increases significantly for those who wear contact lenses overnight even only occasionally. Don’t assume daily disposable contacts are healthier if you practice poor hygiene when handling the lenses or over wear them.
5. Contact lenses should never be rinsed or stored in saline or tap water. I repeat: Never.
6. Always ensure proper disinfection of your contact lenses before putting them in and make sure you’ve washed your hands thoroughly to avoid transferring germs on to the lens or your eye.
7. There are some brands of contact lenses that allow enough overnight oxygen transmission to the cornea that make it safe to wear these lenses while you sleep. Two brands that come to mind are Air Optix Night And Day and Coopervision’s Mediflex Aquafinity 160 or Harmony lenses.

For more tips to wearing contact lenses, see our parents’ guide to contact lenses. If you’re still deciding whether contact lenses are right for you, see our list of things to know and consider about contact lenses.