Dark Mode Reading on iPhone: How to Use True Black on OLED Screens

You turn off the lights, open your book, and the screen still glows like a flashlight. Most reading apps call their night theme "dark mode," but what you actually get is a dark grey page on a slightly less dark grey background. On an OLED iPhone that grey is a missed opportunity, because the panel is capable of going truly black, pixel by pixel, and a real dark theme feels completely different to read at night.

This guide explains what true black actually does on an OLED screen, why it matters for both your eyes and your battery, and how to set it up so your reader switches to a black page on its own at sunset. Everything here applies to iPhone and iPad running justRead, and the same settings work whether you read EPUBs or PDFs.

Why "dark mode" usually disappoints on OLED

Every iPhone since the iPhone X (with the exception of a couple of LCD models) uses an OLED display. The important detail is how OLED makes light. Each pixel produces its own light, so a black pixel is not a dark pixel, it is an off pixel. No backlight shines through it. That is different from an LCD, where a single backlight is always on behind the whole screen and "black" is really just the panel blocking as much of that light as it can.

This is why a lot of dark themes feel underwhelming. If the background is #1c1c1e (Apple's standard dark grey) rather than pure black, every one of those pixels is still lit. You lose the deepest contrast OLED can give you, and on a phone held a few inches from your face in a dark room, that lit grey is exactly the glow that keeps your eyes working harder than they need to.

True black, the pure #000000 value, is what lets the OLED panel switch those pixels off entirely. The result is text floating on genuine darkness, which is both easier to look at late at night and measurably lighter on the battery.

The battery side

Because OLED pixels draw power individually, the darker your screen, the less power it uses. A reading page is mostly background with a thin layer of text on top, so a true-black background means the vast majority of the screen is drawing close to zero power. You will not get this benefit from a grey theme, because grey pixels are still on. Reading is also a low-brightness, long-duration activity, which is exactly the kind of use where those savings add up over an evening.

This effect is real but modest, so do not expect your battery to double. Think of it as a small bonus that comes free with a setting that already makes reading more comfortable.

The contrast and glare side

Contrast is the difference between your text and its background. Pure white text on pure black is the highest contrast a screen can produce, which makes letters crisp without forcing you to raise the brightness. In a dark room that matters more than it sounds, because a bright screen against dark surroundings is the classic recipe for eye fatigue. A true-black page lets you drop the brightness lower while keeping the text perfectly readable.

One honest caveat: maximum contrast is not automatically the most comfortable for everyone. Some people find pure white on pure black a little harsh and prefer a soft off-white text or a very dark grey that is not quite black. The point of a good reader is that you get to decide, rather than being stuck with whatever grey the app shipped with.

How to set up dark mode in justRead

justRead handles colors through its display settings, and you have three levels of control: ready-made presets, fully custom colors, and automatic switching based on time of day. Here is how to use each.

Choose a color preset

1. Open any book and tap the center of the screen to bring up the reading controls.
2. Open the text or display settings (the typography and appearance panel).
3. Find the color presets. You will see options that cover light and dark themes.
4. Tap the dark preset to apply it immediately. The page updates live, so you can see the change before you commit to it.

The presets are the fastest way to get a comfortable night theme, and for a lot of people they are enough. But if the built-in dark theme is a touch too grey for your OLED, the next step is where true black comes in.

Set a true-black background manually

1. In the same color settings, choose the option to customize the text and background colors.
2. Open the background color picker and set it to pure black. If the picker accepts a hex value, enter #000000; otherwise drag the brightness all the way down to zero.
3. Set the text color to white, or to a soft off-white if pure white feels too sharp for your eyes.
4. Apply it and read a page or two at your normal nighttime brightness to check the balance.

Because the background is now genuinely #000000, your OLED panel turns those pixels off and you get the deep black, lower power draw, and high contrast described above. Custom colors are saved, so you only do this once.

A small tip: if you read in different conditions, remember that justRead can keep settings per book. You can give a heavily illustrated book a different treatment from a plain novel without changing your default everywhere.

Switch themes automatically with sunrise and sunset

The best dark mode is the one you never have to think about. justRead's color presets include light, dark, sunrise, and sunset automation, which means the app can change its theme on its own as the day goes on.

1. In the color preset settings, turn on the automatic switching option.
2. Assign your daytime (light) theme and your nighttime (dark or true-black) theme.
3. Let the sunrise and sunset behavior handle the rest. The app moves to your dark theme as evening comes and back to your light theme in the morning.

Set this up once and you stop fiddling with settings entirely. You open your book in the afternoon and read on a light page; you open the same book after dinner and it is already on a black background. This is the setup most night readers actually want, because the comfort is automatic instead of manual.

If you would rather it follow your phone's overall appearance instead of the clock, you can tie the theme to the system light or dark setting so it matches whatever the rest of iOS is doing.

Tuning the page for nighttime reading

True black is the foundation, but a few more settings make a dark page genuinely easy on the eyes during a long evening session.

Drop the brightness lower than you think. The whole advantage of high-contrast white-on-black is that you can read clearly at a low brightness. If you also use iOS's True Tone and Night Shift, the warmer tone at night pairs well with a dark theme. For the absolute lowest brightness, the iOS accessibility setting "Reduce White Point" lets you dim the screen below the normal slider's floor, which is useful for reading in a pitch-dark room.

Use the margins to your advantage. justRead lets you set separate margins for portrait and landscape. A slightly wider margin keeps the text away from the very edge of the screen, so the bright letters are not running right up against your peripheral vision. It is a subtle thing, but it helps when you are reading on your side in bed.

Give the lines a little room. A small bump in line spacing reduces the sense of a dense wall of text, which matters more when you are tired. Pair that with a font size that does not make you squint and a dark page becomes something you can stay in for an hour without noticing.

Pick a comfortable typeface. justRead ships with a library of over 200 fonts, grouped by family so you can scroll to the one that reads particularly well for you in white-on-black and switch to it in a tap. If you want to go deeper on fonts, themes, and layout, the customization options page covers what is adjustable, and our guide to the best customizable EPUB reader for iPhone compares how far different apps let you push it.

What dark mode does not fix

A true-black theme cuts glare and lowers the light hitting your eyes, but it does not change the fact that you are staring at a fixed distance for a long stretch. The single biggest cause of tired eyes during reading is not screen color, it is the lack of breaks. Your focusing muscles stay locked at the same near distance, and that is what leaves your eyes feeling strained no matter how good your theme is.

The simplest fix is the 20-20-20 habit: every 20 minutes, look at something 20 feet away for 20 seconds. It gives those muscles a moment to relax. justRead has a built-in break timer for exactly this, and we cover the why and how in the 20-20-20 rule for reducing eye strain guide. Dark mode and a break habit together do far more than either one alone.

It is also worth being clear about what a reading app cannot do for you. justRead does not read books aloud, so dark mode is about looking at the page comfortably, not avoiding the screen entirely. If your goal at night is to rest your eyes completely, the answer is a break, not a different background color.

FAQ

Does justRead support true black mode on iPhone?

Yes. Beyond the built-in dark preset, you can set the background color manually to pure black (#000000). On an OLED iPhone that switches the background pixels off, giving you genuine black rather than dark grey.

Will dark mode actually save battery on my iPhone?

On an OLED iPhone, yes, because black pixels are switched off rather than lit. A reading page is mostly background, so a true-black theme keeps most of the screen drawing almost no power. The saving is modest, not dramatic, but it is real and it comes free with a more comfortable page. It does not apply on the few older LCD iPhones, where the backlight is always on.

Can justRead switch to dark mode automatically at night?

Yes. The color presets include sunrise and sunset automation, so the app can move to your dark or true-black theme in the evening and back to a light theme in the morning on its own. You can also tie the theme to your phone's system light or dark setting instead of the clock.

Should the text be pure white or off-white on a black background?

That is personal. Pure white gives the highest contrast and the crispest letters, which many people prefer. Others find it slightly harsh in a dark room and read more comfortably with a soft off-white. justRead lets you pick the exact text color, so try both and keep whichever your eyes prefer.

Does dark mode fix eye strain completely?

No. It reduces glare and the amount of light your eyes take in, which genuinely helps, but most reading fatigue comes from holding your focus at one distance for too long. Taking regular breaks does more for that. See the 20-20-20 break guide for the habit that pairs best with a good dark theme.

Does this work for PDFs too?

The color and theme settings are built around reflowable EPUB text, where the app controls the page. PDFs are read-only and keep their original fixed layout, so a PDF with a white page background will still show that page as the document author made it. For text-heavy reading at night, EPUB gives you the full control described in this guide.

Read comfortably after dark

If you read on an OLED iPhone at night, a true-black background is the single setting that makes the biggest difference, and once you add sunrise and sunset automation you never have to touch it again. justRead is built to give you that level of control over colors and themes rather than locking you into one grey night mode. You can see how the theme and color settings fit together on the dark mode reader page, and there is no rush; the setup takes about a minute and then it just works every evening.

To go further, explore the full customization options for fonts, margins, and layout, or read our guide to the best customizable EPUB reader for iPhone and the 20-20-20 eye-strain guide for the habit that keeps long night sessions comfortable.