What does reading in dim light actually do to your eyes?
Generations of parents warned that reading by flashlight or candle would wreck your eyes, and Samuel Pepys blamed candle-light for his failing sight. Reviews of the evidence find temporary strain, not lasting damage.
8 established, 2 disputed, 2 debunked, 1 unresolved. We do not pick an answer; the evidence places each claim. How we decide
40 citations from 8 independent sources - 32 echo the same voices and count once. Graded A1-D1.
Added 3 Jul 2026 - updated 29 Sept 2026
What the four states mean
- Establishedsupported, uncontested
- Disputedcredible sources disagree
- Debunkedrefuted by the evidence
- Unresolvedno settled answer
Established 8supported, uncontested
Indiana University School of Medicine researchers included 'reading in dim light ruins your eyesight' among seven beliefs reviewed in 'Medical Myths Even Doctors Believe' in the British Medical Journal's Christmas issue.▰▰▰▱▱ likely2 points
Supports- In a study entitled “Medical Myths Even Doctors Believe” published in the Christmas issue of the British Medical Journal, Indiana University School of Medicine researchers explored seven commonly held medical beliefs.Medical myths even doctors believe (Indiana University news release, EurekAlert!, 20 Dec 2007) summary
- We selected seven for critical review: People should drink at least eight glasses of water a day We use only 10% of our brains Hair and fingernails continue to grow after death Shaving hair causes it to grow back faster, darker, or coarser Reading in dim light ruins your eyesightVreeman & Carroll, 'Medical myths', BMJ 2007;335:1288 (full text via PMC) authoritative
In dim light the iris opens the pupil as wide as possible while the eye tries to focus the small amount of light onto the retina.▰▰▰▱▱ likelysummary-sourced2 points
Supports- Your iris is simultaneously trying to open your pupil as wide as possible to let in more light, while your eye is also trying to focus that small amount of light hitting the words onto your retina just right so that you can distinguish between the words and the page itself.Reading in Dim Lighting Will Not Damage Your Eyes (Today I Found Out) summary
- The American Academy of Ophthalmology has stated repeatedly that reading in low light is like exercising with weights that are too heavyEye Doctors Keep Debunking the Dim Light Vision Myth (Real Story Check) summary
Suboptimal lighting can make focusing feel difficult, reduce blinking and cause discomfort from drying, but these effects do not persist and are unlikely to permanently change the eyes.▰▰▱▱▱ likely3 points
Supports- Suboptimal lighting can create a sensation of having difficulty in focusing. It also decreases the rate of blinking and leads to discomfort from drying, particularly in conditions of voluntary squinting.Vreeman & Carroll, 'Medical myths', BMJ 2007;335:1288 (full text via PMC) authoritative
- The important counterpoint is that these effects do not persist.Vreeman & Carroll, 'Medical myths', BMJ 2007;335:1288 (full text via PMC) authoritative
- Although it can cause eye strain with multiple temporary negative effects, it is unlikely to cause a permanent change on the function or structure of the eyes.Vreeman & Carroll, 'Medical myths', BMJ 2007;335:1288 (full text via PMC) authoritative
People blink less when staring at screens or doing other near work such as reading; a normal rate of around 15 blinks a minute can be cut in half.▰▰▱▱▱ likely3 points
Supports- Normally, we blink around 15 times per minuteDigital Devices and Your Eyes (American Academy of Ophthalmology) analysis
- this “blink rate” can be cut in half when staring at screens or doing other near work activities (like reading).Digital Devices and Your Eyes (American Academy of Ophthalmology) analysis
- The reason discomfort from screens is so common, is that we blink less when we stare at our devices.Digital Devices and Your Eyes (American Academy of Ophthalmology) analysis
Samuel Pepys attributed pain in his eyes to reading and writing by candle-light, and later ended his diary because writing it was undoing his eyes.▰▰▱▱▱ likely3 points
Supports- my eyes began to fail me, and be in pain which I never felt to now-a-days, which I impute to sitting up late writing and reading by candle-light.The Diary of Samuel Pepys, 19 January 1663/64 primary
- I was at it to-night, but durst not stay long at it, I being come to have a great pain and water in my eyes after candle-light.The Diary of Samuel Pepys, 1 April 1664 primary
- And thus ends all that I doubt I shall ever be able to do with my own eyes in the keeping of my journal, I being not able to do it any longer, having done now so long as to undo my eyes almost every time that I take a pen in my handThe Diary of Samuel Pepys, 31 May 1669 primary
In school trials, adding outdoor time reduced new myopia: an extra 40-minute outdoor class cut 3-year incidence from 39.5% to 30.4% in Guangzhou, and outdoor recess cut one-year new onset from 17.65% to 8.41% in Taiwan.▰▰▱▱▱ likely6 points
Supports- Cluster randomized trial of children in grade 1 from 12 primary schools in Guangzhou, China, conducted between October 2010 and October 2013.He et al., 'Effect of Time Spent Outdoors at School on the Development of Myopia', JAMA 2015 (abstract) authoritative
- The primary outcome measure was the 3-year cumulative incidence rate of myopiaHe et al., 'Effect of Time Spent Outdoors at School on the Development of Myopia', JAMA 2015 (abstract) authoritative
- The cumulative incidence rate of myopia was 30.4% in the intervention group (259 incident cases among 853 eligible participants) and 39.5% (287 incident cases among 726 eligible participants) in the control groupHe et al., 'Effect of Time Spent Outdoors at School on the Development of Myopia', JAMA 2015 (abstract) authoritative
- For 6 intervention schools (n = 952 students), 1 additional 40-minute class of outdoor activities was added to each school dayHe et al., 'Effect of Time Spent Outdoors at School on the Development of Myopia', JAMA 2015 (abstract) authoritative
- After 1 year, new onset of myopia was significantly lower in the ROC group than in the control group (8.41% vs. 17.65%; P<0.001).Wu et al., 'Outdoor activity during class recess reduces myopia onset and progression in school children', Ophthalmology 2013 (abstract) authoritative
- Elementary school students 7 to 11 years of age recruited from 2 nearby schools located in a suburban area of southern Taiwan.Wu et al., 'Outdoor activity during class recess reduces myopia onset and progression in school children', Ophthalmology 2013 (abstract) authoritative
Good lighting makes it easier to see what you are reading and keeps your eyes from tiring out more quickly.▰▰▱▱▱ likely1 source
Supports- But good lighting can make it easier to see what you are reading and keep your eyes from tiring out more quickly.Common Eye and Vision Myths (American Academy of Ophthalmology) analysis
Even in patients with Sjögren's syndrome, reduced visual acuity associated with strained reading improves when they stop reading.▰▰▱▱▱ likely1 source
Supports- Even in patients with Sjögren’s syndrome (an autoimmune disease that features inflammation in certain glands of the body), decreased functional visual acuity associated with strained reading improves when they stop reading.Vreeman & Carroll, 'Medical myths', BMJ 2007;335:1288 (full text via PMC) authoritative
Disputed 2credible sources disagree
More time on near work is associated with higher odds of myopia in children.▰▰▰▱▱ roughly even chance1 against3 points
Supports- We found that more time spent on near work activities was associated with higher odds of myopia (odds ratio [OR] = 1.14Huang, Chang & Wu, 'The Association between Near Work Activities and Myopia in Children', PLOS ONE 2015 authoritative
- and that the odds of myopia increased by 2% (OR:1.02; 95% CI = 1.01-1.03) for every one diopter-hour (hr) more of near work per week.Huang, Chang & Wu, 'The Association between Near Work Activities and Myopia in Children', PLOS ONE 2015 authoritative
Against- Only two reported that more near work activities increased the risk of developing myopia ... but others found no correlation between near work activities and the incidence of myopiaHuang, Chang & Wu, 'The Association between Near Work Activities and Myopia in Children', PLOS ONE 2015 authoritative
Bright light protects against myopia by stimulating dopamine release in the retina.▰▰▰▱▱ roughly even chance2 against4 points
Supports- The primary hypothesis is that bright light stimulates dopamine release in the retina.Light, Dopamine, and Myopia (Dopavision Insights) summary
- The protective effect of bright light against myopia development is not observed when animals are administered a compound that blocks dopamine receptors.Light, Dopamine, and Myopia (Dopavision Insights) summary
Against- We found that mice exposed to either scotopic or photopic lighting developed significantly less severe myopic refractive shifts ... than mice exposed to mesopic lightingLandis et al., 'Ambient Light Regulates Retinal Dopamine Signaling and Myopia Susceptibility', IOVS 2021 authoritative
- Lens defocus interacted with ambient conditions to differentially alter myopia susceptibility and DA-related genes and proteins.Landis et al., 'Ambient Light Regulates Retinal Dopamine Signaling and Myopia Susceptibility', IOVS 2021 authoritative
Debunked 2refuted by the evidence
Sitting very close to the television damages your eyes.Refuted by
While sitting very close to the television may cause eye strain or give you a headache, it will not damage vision in children or adults.
refuted2 against3 pointsThe claim rested on- Myth: Sitting very close to the TV can damage your eyes.Common Eye and Vision Myths (American Academy of Ophthalmology) analysis
Refuted by- While sitting very close to the television may cause eye strain or give you a headache, it will not damage vision in children or adults.Common Eye and Vision Myths (American Academy of Ophthalmology) analysis
- While using devices will not damage your eyes permanently, staring at them for a long time can cause temporary discomfort.Digital Devices and Your Eyes (American Academy of Ophthalmology) analysis
Reading in dim light causes permanent damage to the eyes.Refuted by
The study authors found no evidence that reading in dim light causes permanent eye damage.
refuted3 against5 pointsThe claim rested on- Even before Abe Lincoln was told that reading in dim candle light was bad for his eyes, people have believed that reading in dim light causes permanent eye damage.Medical myths even doctors believe (Indiana University news release, EurekAlert!, 20 Dec 2007) summary
- In addition to doctors, 56.3% of teachers surveyed by BioMed Central say that in order to maintain good eye health, people should avoid reading in dim lightReading in Dim Lighting Will Not Damage Your Eyes (Today I Found Out) summary
Refuted by- The study authors found no evidence that reading in dim light causes permanent eye damage.Medical myths even doctors believe (Indiana University news release, EurekAlert!, 20 Dec 2007) summary
- The majority consensus in ophthalmology, as outlined in a collection of educational material for patients, is that reading in dim light does not damage your eyes.Vreeman & Carroll, 'Medical myths', BMJ 2007;335:1288 (full text via PMC) authoritative
- It does not harm your eyes to read in dim light.Common Eye and Vision Myths (American Academy of Ophthalmology) analysis
Unresolved 1no settled answer
Whether reading in dim light contributes to myopia is not settled: one review proposed that it could impair ocular growth, a hypothesis described as just beginning to gain scientific credence.▰▰▰▱▱ roughly even chance2 against4 points
Supports- One review article on myopia concludes that increased use of one’s eyes, such as reading in dim light or holding books too close to the face, could result in impaired ocular growth and refractive error.Vreeman & Carroll, 'Medical myths', BMJ 2007;335:1288 (full text via PMC) authoritative
- The author notes that this hypothesis is just beginning to “gain scientific credence.”Vreeman & Carroll, 'Medical myths', BMJ 2007;335:1288 (full text via PMC) authoritative
Against- In the past reading conditions involved even less light, relying on candles or lanterns, so increased rates of myopia over the past several centuries does not necessarily support that dim reading conditions are to blame.Vreeman & Carroll, 'Medical myths', BMJ 2007;335:1288 (full text via PMC) authoritative
- On weekends, myopic children received significantly less scotopic light ( P = 0.024) and less outdoor photopic light than nonmyopic children ( P < 0.001).Landis et al., 'Dim Light Exposure and Myopia in Children', IOVS 2018 authoritative
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