Apple is kind of notorious for hiding important features. On iPads, for example, there are options to shrink the size of the interface to fit more text and graphics onscreen, or switch back to the earlier multitasking system if you don’t like Mac-style windows. The company does deliver a few helpful suggestions via its Tips app, but otherwise, you’re left to discover a lot of customization options on your own.
iPhones are no exception. In fact, if using your iPhone 17 or iPhone Air in low light is bothering you, there may be just a single, somewhat cryptic option you need to change, buried a couple of layers down in the iOS Settings app. While I’m at it, if you don’t have a 17 or Air, I’m going to touch on a few general iPhone settings (and habits) that can make things better for sensitive eyes. You might also benefit if you’re having trouble with reading, or like me, getting to sleep on time can be an ordeal.
The ins and outs of pulse smoothing
What you need to know
Devices based on LED lighting don’t necessarily control brightness the way you’d expect. When you imagine a light brightening or dimming, you’re probably picturing an incandescent bulb, which changes strictly based on the amount of power flowing through it.
Certainly, power levels are still important on LED devices, but often what’s going on is something called pulse width modulation, or PWM for short. It’s a term I’m familiar with from electric unicycles, believe it or not. In the context of things like smart bulbs or your phone, though, it refers to LEDs turning off and on at different rates to trick your brain into thinking you’re seeing a brighter or dimmer image. This can actually be vital with smartphones, since OLED panels present visual problems if you simply reduce power flow.
A minority of people are physically sensitive to low PWM rates, which many devices have relied on for years. If your iPhone sometimes triggers symptoms like headaches or nausea, this may be why.
Most people won’t notice PWM at all. At higher brightness levels, your iPhone’s screen is flickering so fast that the effect tends to be indiscernible. As brightness ramps down, though, you’re more and more likely to catch it, if not necessarily consciously. There’s a far more serious risk, however. A minority of people are physically sensitive to low PWM rates, which many devices have relied on for years. If your iPhone sometimes triggers symptoms like headaches or nausea, this may be why. In extreme cases, this sensitivity may lead to crippling migraines.
Display changes on the iPhone 17 lineup and the iPhone Air mean that it’s now possible to counteract the effects of PWM. Specifically Apple has implemented an option called Display Pulse Smoothing, which you can toggle on under Settings -> Accessibility -> Display & Text Size. To make things extra clear, you will only find this option on the iPhone 17, 17 Pro, 17 Pro Max, and iPhone Air. It’s not available on the iPhone 17e, presumably because that model uses older screen tech. Apple’s budget devices often reuse parts from outdated flagship products.
Avoid turning on Display Pulse Smoothing if it’s not distracting you or causing some of the symptoms I’ve mentioned. Apple warns that disabling PWM can negatively affect the low-brightness performance of an iPhone “under certain conditions.” Rather vaguely, the company doesn’t explain what those are. Presumably it’s referring to the same issues that led to phone makers adopting PWM in the first place.
What else can you do to make an iPhone easier on the eyes?
Some basic tips
Perhaps the simplest tactic is making sure Auto-Brightness is on, under the same menu as Pulse Smoothing. This adjusts brightness based on ambient lighting conditions, not only helping your eyes, but prolonging battery life. You can and should still adjust general brightness in Control Center — Auto-Brightness will keep levels relative. My own suggestion is to aim for about 50%, which on an iPhone 16 or 17 will still be plenty readable under most circumstances.
Speaking of reading, if you’re struggling with that, you may want to head over to Settings -> Accessibility -> Display & Text Size -> Larger Text. Drag the slider to a size that’s comfortable without going overboard. If you go too far, you’ll see very little content onscreen in apps and webpages. Worse, this can actually interfere with buttons in apps, which are designed with Apple’s standard font size in mind.
Be sure to set a Night Shift schedule under Settings -> Display & Brightness. When it’s active, this feature shifts your display towards warmer tones, reducing the amount of blue light you’re exposed to. The effects of blue light are sometimes overstated — nevertheless, it’s the worst kind of light for your sleep patterns, since it’s very effective at suppressing melatonin production. If you want the full effect, schedule Night Shift to start at least 3 hours before you go to bed, and set its tone to be as warm as possible. Schedule it to turn off when you normally wake up.
Realistically, the best way to alleviate eye strain is all too simple: taking a break. One standard approach is the “20-20-20” rule, which involves staring at something 20 feet away for 20 seconds every 20 minutes.
One last option I’d recommend is Increase Contrast, again under Settings -> Accessibility -> Display & Text Size. This boosts the difference between foreground and background colors in apps. This can potentially be uncomfortable for some people, but I actually quite like it — it makes text and images “pop” in a way I’d like to have standard on iPhones.
Anything else I might suggest boils down to habits, rather than settings. You should, for instance, avoid looking at any bright display in a dark room, because that degree of contrast can be painful. Even a dim lamp will help ease things. If you’re trying to get to sleep, but need iPhone videos to wind down, you should at least turn brightness down as far as you can tolerate, and consider closing your eyes and listening instead. I’m doing exactly that on many nights.
Realistically, the best way to alleviate eye strain is all too simple: taking a break. One standard approach is the “20-20-20” rule, which involves staring at something 20 feet away for 20 seconds every 20 minutes. The reason you’re staring at something in the distance is to relax the muscles needed to focus. Otherwise, though, one of the major benefits is allowing yourself to blink more often, reducing dryness. And if you’re dealing with regular headaches, this may do the trick, as either tense muscles or the effects of PWM could be responsible.
If you have trouble forcing yourself to take a break, it may be time to turn on Downtime and App Limits for yourself under Settings -> Screen Time. A few apps, like YouTube, will let you set their own sleep timers, ensuring that you can’t keep binging videos indefnitely — at least without noticing how long it’s been.
