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Sleeping in contact lenses: what the real risk is

A nap on the sofa or a night away from home, and the lenses stay in. What studies say about the risk of corneal infection when you sleep in lenses, even those designed for night-time.

By the editorial teamUpdated 7 min read10 studies and sources citedAI-generated text
Illustration Sleeping in contact lenses: under the closed eyelid, microbes find room between the lens and the cornea. False that it is harmless: in studies, sleeping in lenses multiplied the risk of a corneal infection.

You fall asleep on the sofa after dinner, or you get home late and put everything off until the morning. The lenses stay in your eyes for a few hours and on waking everything seems fine, apart from a little dryness. Experiences like this give rise to a widespread belief: with contact lenses you can sleep, at least now and then, without consequences.

False, according to the studies. Sleeping in lenses is one of the main risk factors for microbial keratitis, a rare infection of the cornea that can leave lasting damage1,5. The risk remains low in absolute terms, but with lenses kept in overnight it is multiplied.

In brief

  • In a large London study, sleeping in lenses was associated with a risk of microbial keratitis 5.4 times higher, with any type of lens1.
  • In Australia there were about 2 cases a year per 10,000 wearers of soft lenses used only in the daytime, and from 19.5 to 25.4 among those who also wore them at night2.
  • Even daily lenses kept in occasionally during sleep were associated with more infections2,3.
  • Lenses that are more permeable to oxygen have not reduced the frequency of infections over the last thirty years6.
In this article
  1. True or false: can you sleep in contact lenses?
  2. How much the risk increases, in absolute numbers
  3. But there are lenses approved for night-time
  4. What the international reviews say
  5. Frequently asked questions
  6. Sources

True or false: can you sleep in contact lenses?

The idea that sleeping in lenses is harmless is understandable: most of the time, on waking, nothing happens. But infections of the cornea are rare, and to see a rare risk you need large studies, comparing hundreds of patients with thousands of healthy people.

The study

The London study: 367 cases compared

A two-year prospective case-control study, begun in 2003 at Moorfields Eye Hospital in London. The researchers compared 367 lens wearers with microbial keratitis with over 1,700 wearers without infection: 1,069 hospital patients with other conditions and 639 people chosen at random from the population. Sleeping in lenses, of any type, was associated with a risk 5.4 times higher. It is a relative risk: it multiplies a starting probability that remains low1.

The same pattern is found in France. A study of 2,267 people, 1,198 with keratitis and 1,069 without, found that among those using daily lenses occasionally sleeping in the lenses was associated with odds of infection about 16 times higher3. It is a relative estimate that should be taken with caution, but the direction matches that of the other studies.

How much the risk increases, in absolute numbers

To give the proportions, we need disease rates. An Australian study counted all the new cases in the country for one year and compared them with the number of wearers, obtained from a telephone survey of almost 36,000 people2. The result, for every 10,000 wearers in a year:

How the lenses are usedCases of keratitis
Soft lenses, daytime only1.9
Daily disposable lenses, daytime only2.0
Daily disposable lenses, sometimes overnight4.2
Soft lenses, overnight19.5
Silicone hydrogel lenses, overnight25.4

A loss of vision occurred in 0.6 wearers per 10,0002. In Spain, a register of 32 hospitals with 304 cases found sleeping, swimming and showering in the lenses among the most common habits; overnight wear was associated with more corneal opacities, scars that can cloud vision4. In the United States, the Centers for Disease Control described six cases in which sleeping in the lenses was the main risk factor: among the consequences were very frequent antibiotic eye drops, many follow-up visits and lasting damage to the eye5.

But there are lenses approved for night-time

True, and it is the part of truth in the myth. There are lenses in materials that are highly permeable to oxygen authorised for extended wear, day and night, and rigid lenses to be worn only during sleep to reshape the cornea, orthokeratology. But oxygen is not everything. In the Australian study overnight wear of silicone hydrogel lenses was associated with 25.4 cases per 10,000 wearers a year2. In 2021 a working group of the American Academy of Optometry concluded that, over thirty years, the rate of microbial keratitis has remained stable despite the new technologies, that extended wear significantly increases the risk and that orthokeratology lenses could increase it in children, especially for Acanthamoeba infections6.

Those who use lenses designed for night-time therefore do so with a higher risk than lenses taken out in the evening, accepted together with the ophthalmologist or contact lens specialist and accompanied by regular check-ups. The TFOS report on the lifestyle of contact lens wearers, an international review from 2023, lists both sleeping in the lenses and skipping check-up visits among the choices that can harm the eye7.

What the international reviews say

The reviews of recent years agree. According to the international CLEAR report, about one wearer in three experiences some complication, almost always mild8; infections are rare, but overnight wear is among the factors that explain the largest share of cases10. Water is the other big chapter, and we describe it in the article on lenses, showers and swimming pools.

When to talk to an ophthalmologist

  • The same day: a painful, red eye, with watering, sensitivity to light or blurred vision, especially on waking after sleeping in the lenses. These are the ways microbial keratitis usually presents9.
  • In case of severe pain and vision that drops, if you cannot reach an ophthalmologist, call 112 or go to the emergency department: the other warning signs are on the page about eye emergencies.

Frequently asked questions

What happens if I sleep one night in my contact lenses?

Most of the time nothing happens: even among those who sleep in their lenses, infection remains a rare event2. But sleeping in the lenses, even occasionally, is associated with higher odds of keratitis2,3.

Is a half-hour nap in lenses dangerous?

We do not know precisely: the studies we have cited do not distinguish short naps from a whole night. We do know, however, that even occasional overnight wear was associated with more infections2,3.

Can extended-wear lenses be kept in at night?

They are authorised for it, but in the studies overnight wear remained associated with a higher rate of infection than lenses taken out in the evening2,6. It is a choice to be made with the professional who looks after the lenses, together with check-ups7. To choose between the different types there is the article on contact lenses.

Sleeping in lenses almost never leads to an infection. But it is a habit that, study after study, multiplies a low starting risk1,2,3.

Sources

  1. Dart JK, Radford CF, Minassian D, Verma S, Stapleton F. Risk factors for microbial keratitis with contemporary contact lenses: a case-control study. Ophthalmology. 2008;115(10):1647-54, 1654.e1-3. doi:10.1016/j.ophtha.2008.05.003 · PubMed 18597850
  2. Stapleton F, Keay L, Edwards K, Naduvilath T, Dart JK, Brian G, et al. The incidence of contact lens-related microbial keratitis in Australia. Ophthalmology. 2008;115(10):1655-62. doi:10.1016/j.ophtha.2008.04.002 · PubMed 18538404
  3. Sauer A, Greth M, Letsch J, Becmeur PH, Borderie V, Daien V, et al. Contact Lenses and Infectious Keratitis: From a Case-Control Study to a Computation of the Risk for Wearers. Cornea. 2020;39(6):769-774. doi:10.1097/ICO.0000000000002248 · PubMed 31990844
  4. Ispizua Mendivil E, Durán de la Colina JA. Infectious keratitis associated with contact lens wear: REGINFECOR multicenter study. Arch Soc Esp Oftalmol (Engl Ed). 2024;99(6):237-247. doi:10.1016/j.oftale.2024.04.004 · PubMed 38588998
  5. Cope JR, Konne NM, Jacobs DS, Dhaliwal DK, Rhee MK, Yin J, et al. Corneal Infections Associated with Sleeping in Contact Lenses – Six Cases, United States, 2016-2018. MMWR Morb Mortal Wkly Rep. 2018;67(32):877-881. doi:10.15585/mmwr.mm6732a2 · PubMed 30114003 · PMC
  6. Szczotka-Flynn LB, Shovlin JP, Schnider CM, Caffery BE, Alfonso EC, Carnt NA, et al. American Academy of Optometry Microbial Keratitis Think Tank. Optom Vis Sci. 2021;98(3):182-198. doi:10.1097/OPX.0000000000001664 · PubMed 33771951 · PMC
  7. Jones L, Efron N, Bandamwar K, Barnett M, Jacobs DS, Jalbert I, et al. TFOS Lifestyle: Impact of contact lenses on the ocular surface. Ocul Surf. 2023;29:175-219. doi:10.1016/j.jtos.2023.04.010 · PubMed 37149139
  8. Stapleton F, Bakkar M, Carnt N, Chalmers R, Vijay AK, Marasini S, et al. CLEAR – Contact lens complications. Cont Lens Anterior Eye. 2021;44(2):330-367. doi:10.1016/j.clae.2021.02.010 · PubMed 33775382
  9. Linaburg TJ, Hammersmith KM. Contact Lens-Related Corneal Infections. Infect Dis Clin North Am. 2024;38(4):795-811. doi:10.1016/j.idc.2024.07.010 · PubMed 39271302
  10. Stapleton F. Contact lens-related corneal infection in Australia. Clin Exp Optom. 2020;103(4):408-417. doi:10.1111/cxo.13082 · PubMed 32363626

Study titles are given in their original language of publication. The superscript numbers in the text refer to these sources; citation details come from PubMed (National Library of Medicine).

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