How Much Light Do You Really Need When Reading?

“Turn on the light! You ruin your eyes! “ I grew up with warnings like this, followed by the flip of a switch almost every time my mom found me head over heels in a book. She never listened to my arguments that I could see the pages perfectly. Mom’s logic was simple and unwavering: if I hadn’t turned on more lights, I would have injured my eyes and potentially lost my greatest pleasure in life — my ability to read.

Mom’s logic was also wrong, although this is a high mileage myth. In 1604, an expert no less than the Dutch astronomer and “founder of modern optics” Johannes Kepler blamed the amount of time he had spent studying for his myopia. There is a small leap from here to suggest that insufficient lighting while reading can make the situation worse (although one doctor suggests that parents mostly used threats to get their children to sleep).

However, a myth has emerged that reading in dim light is harmful, but this is simply not true. So says Dr. Sunir J. Garg, Clinical Representative for the American Academy of Ophthalmology (AAO) and professor of ophthalmology at the Wills Eye Hospital in Philadelphia, who assures us that there is no scientific evidence that reading in dim light can harm your health. vision or the health of your eyes in general.

“This is not a safety issue, [as much] as a personal comfort issue,” Dr. Garg tells me. In fact, in his own home, his wife reads at night, using only a backlit e-reader or the focused beam of a desk lamp. (He prefers a constant overhead light.)

Our eyes are much tougher than their softness would suggest (reminiscent of that scene in Kill Bill: Volume II ), although vision problems are not something to squint at. Read on using any amount of light you want to find out more.

Reading “in the dark” doesn’t hurt your eyes, period

One way to stop repeating a myth read in the dark is to ask them exactly how a lack of light can even harm their eyes. This is not to say that people’s eyes start to melt, like scoops of ice cream when they read in a dim room, or blindness suddenly sets in in the middle of a book (just when you were probably getting down to good).

Usually the person warning you implies that repeated reading in low light can cause refractive errors over time: the medical term for vision problems. There are four main types of refractive errors: myopia (nearsightedness), farsightedness (farsightedness), astigmatism (general blurring caused by changes in the shape of the cornea and lens), and presbyopia (age-related myopia problems that usually require reading glasses). All of these problems arise from changes in the shape of the eye that prevent the incident light from focusing on the back of the retina. Three-quarters of these conditions are associated with difficulty seeing objects up close: this is the vision problem that you will most notice when reading.

Myopia is by far the most common vision problem in the world. In addition, since the second half of the 20th century, it has been growing at a shocking pace . Research shows that by 2050, more than half of the world’s population may have some degree of myopia. In the United States, myopia has increased from 25 percent of the population in 1971 to about 40 percent today, a 14 percent increase from 2000 alone. However, the disease has increased particularly sharply in East Asia, where myopia rates reach 80-90 percent of children and adolescents in China, Japan, Singapore, South Korea and Taiwan (compared with 10-20 percent in some parts of the country). 1950s)

Part of this increase may be attributed to greater awareness and access to vision exams and glasses in developing countries, especially for children ages 6 to 12 , when many people first need corrective lenses. However, even with this possibility, the growth rate is too high for genetics, which was the main culprit in the 1960s and 1970s, to be the only cause.

Heredity remains one of the most important predictors of myopia, and studies have identified over 100 genetic markers associated with the condition. However, scientists recognize that children inherit not only genes, but also lifestyle from their parents, and some studies have argued that the number of hours spent studying (or rereading Harry Potter ) increases the risk of myopia, especially in primary and secondary school.

However, none of these studies found any specific link between myopia and the amount of light used when doing so-called near work, such as reading, even at night. “As far as we know, it doesn’t matter from an eye health standpoint,” says Dr. Garg. “It really comes down to what works for you and is most comfortable.”

There is never too much light – not even blue light

When I read in bed, the table lamp on the bedside table is parallel to my eyes, so the light often falls on them rather than above them. When I ask Dr. Garg about this, he tells me not to worry; my eyes do a great job with these rays.

But what if the direct light is blue light from an e-reader, tablet, or smartphone? “There is very little or no high-quality scientific evidence to suggest that blue light from our screens is a problem for us,” he says. Blue light does affect our circadian rhythms, this is true, although it’s worth noting that one of the most cited studies found that participants exposed to blue light at night fell asleep, on average, just 10 minutes later than controls. (Other scientists argue that the study’s laboratory conditions grossly underestimated the amount of natural and artificial light most people experience over a 24-hour period, which might exaggerate the results.)

“Humans have been exposed to blue light for thousands or tens of thousands of years,” notes Dr. Garg, “because blue light is part of the sunlight.”

He continues, “On a typical outdoor work day, we get a lot more blue light than we ever did when looking at a screen for eight hours a day.” After all, a sunny afternoon is 100,000 times brighter than our computer screens. This means that using dark mode or night settings on your screens won’t do any harm, but it probably won’t do much either. And don’t waste money on blue light blocking glasses unless you enjoy spending money on things that don’t work. No judgment!

You especially want to avoid glasses with a blue light filter when you are outdoors, because one of the most intriguing hypotheses about the rise in myopia worldwide relates to insufficient outdoor lighting. Several studies have shown that children who spend more time outdoors develop less myopia . It is not clear why this is so, although two possible explanations are the relative brightness of sunlight versus indoor lighting and the fact that macro photography is more often done indoors. Some scientists even insist that exposure to light in itself may not be the real benefit of spending time outdoors, but some other factor. This has not stopped some countries, such as Taiwan, from introducing compulsory outdoor activities for young children; One study found that, two years after the initiative was taken, myopia in children aged 5-6 in one Taiwanese city dropped by almost 50 percent.

However, now is a good time to remind you that you need to wear sunglasses that protect against UV light, and do not look directly at the sun, when you’re all-still come out of his cave with Wi-Fi. Doing the latter for a few seconds can cause temporary damage, while about 100 seconds of sun exposure can cause permanent damage ; Symptoms range from light sensitivity, pain, blurred vision, and even blindness. Wearing UV protective sunglasses outdoors is just as important as using sunscreen.

Reading in any light can cause discomfort but not damage

No matter what kind of light you use, long periods of working around you will inevitably cause eye strain – a generic term for the myriad of symptoms that can occur with eye strain . These symptoms include :

  • blurred vision
  • tearing
  • dryness
  • headache
  • pain in the neck, shoulder and facial muscles
  • difficulty concentrating
  • burning or itching in the eyes

One of the main causes of eye strain is blinking less when we focus on something. “If you look at a young child playing a video game, he doesn’t blink,” says Dr. Garg. “Physically, the same thing happens with adults.”

Blinking wets the eyes with tears, which contain the nutrients and oxygen needed for eye health. We usually blink 12 to 15 times per minute , but when using a computer, this frequency can drop by 60 percent . Reading a book can be even worse.

At the same time, we do not blink, we also wear out our eyes by holding them in the same position for a long period of time. Dr. Garg likens this to stretching an arm or staying in the same position for a long time.

As unpleasant as these sounds of dryness and fatigue are, they are temporary discomfort, with relatively easy fixes and no permanent consequences. Dr. Garg says that repetitive eye strain, unlike repetitive extremity straining, does not result in cumulative or permanent damage. Moreover, not everyone experiences eye strain; it varies from person to person and may improve or worsen (usually the latter) with age.

If, after a couple of hours, your eyes start to feel sandblasted, you can do two things: moisturize your eyes and let them rest. To lubricate your eyes, start with artificial tears or moisturizing drops. Any brand will work, but contact lens wearers should use lens-specific moisturizing drops as other types can cloud your vision. If you live in a particularly arid environment, you may also want to consider using a humidifier. Again, this has more to do with personal preference and individual experience than need. Dr. Garg, for example, finds that dry winters in Philadelphia and central heating crack his skin and burn his eyes, so he uses humidifiers at home.

To give your eyes a rest, follow the 20-20-20 rule : stare at an object at least 20 feet away every 20 minutes for at least 20 seconds. This is for the eyes the equivalent of walking around the office and stretching your muscles to soften the effects of sedentary work. It also gives the eye muscles the ability to switch from the slightly squinting position to which they fall when working side by side. (Another myth to debunk: Your eyes won’t get stuck if you cross them.)

If you find dry eyes particularly impacted by your quality of life and time at work, Dr. Garg recommends consulting an eye doctor. “What we can do now … is much better than it was even five years ago,” he says.

The best way to take care of your eyes is to take care of your body.

One of the ironic features of eye health is that we experience the discomfort of eye strain more easily than many severe and persistent eye conditions such as macular degeneration, glaucoma, and diabetic retinopathy. “Some eye conditions do not have much pain, and some do not even cause vision loss until significant progress is made,” says Dr. Garg.

Screening recommendations are everywhere when it comes to eyes, in part because people with corrective lenses generally need more frequent visits than people with 20/20 vision, mainly because they need to regularly check and change their prescriptions. The AAO recommends that adults who have no symptoms or risk factors for eye disease have a baseline examination at age 40, while the American Optometric Association (AOA) recommends annual examinations for all adults 18 years of age and older who have risk factors, and at least every two years for adults 18 to 64 years old. Risk factors include :

  • a family history of medical conditions such as macular degeneration or glaucoma
  • high blood pressure
  • diabetes
  • race and ethnicity, especially for glaucoma
  • age (CDC recommends having eye exams every two years for adults aged 60 and over)

However, while regular eye exams are important, one of the best things you can do for your eyes is to follow general health guidelines . “What’s good for the whole body is great for the eyes,” says Dr. Garg.

So don’t smoke. (Or quit smoking if you do.) Eat at least three servings of leafy green vegetables and foods high in omega-3 fatty acids (especially fish) per week. Engage in approximately 30 minutes of moderate cardiovascular exercise ( such as brisk walking) three times a week. “For most people, this is all they need for overall eye health,” says Dr. Garg.

And don’t worry about the amount of light you use when reading – unless you need to disprove the hypochondriac in your family. Then be sure to show them the piece.


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