Reading PDFs at night without wrecking your eyes
In short: Dark mode on a Mac darkens the window but leaves a PDF page white, and inverting the whole screen turns photos into negatives and flips colours. A better approach is to darken only the page and keep its colours: Better PDF's night reading (⇧⌘N) does that for free: it dims scanned and photographed pages instead of inverting them, and leaves the rest of the window alone.
To read PDFs at night on a Mac, darken the page itself rather than the whole screen, and turn the screen brightness down to match the room. Dark mode leaves PDF pages white, and inverting the screen ruins photos and colours. Better PDF’s night reading (⇧⌘N) darkens only the page and keeps its colours.
That is most of the advice. The rest explains why the obvious fixes go wrong.
Why doesn’t dark mode darken the PDF?
Dark mode is about the app, not the document. Turn it on in System Settings and the window, the sidebar and the toolbar go dark. The page stays exactly as its author made it, which for nearly every PDF means black text on a white sheet.
So in a dark room you get a dark frame with a bright rectangle in the middle of it. That can feel worse than an all-white window: your eyes adjust to the dark surround and then get hit by the page. It is like reading a paperback under a single spotlight.
Why is inverting the whole screen the wrong fix?
macOS has a colour inversion switch in its Accessibility settings. It does turn a white page black. It also does a few things you will not want.
Photos become negatives. A photo in a report, a product shot in a manual, a scanned page of a book: all of them turn into film negatives. Faces go blue-green.
Colours flip to their opposites. Inversion flips every colour, not just the light and dark. A red “overdue” stamp turns cyan. A green tick turns pink. Charts that rely on colour stop making sense, and yellow highlights turn dark blue, which is hard to read through.
Everything inverts, not just the page. Inversion flips your wallpaper, the menu bar and every other window too. Smarter modes that try to skip images help on web pages, but do little inside a PDF, where the photo is part of the page rather than a separate image.
For a page of plain text, inversion is fine. Most PDFs worth reading at night are not only plain text.
What does night reading in Better PDF do differently?
Press ⇧⌘N, or choose View › Appearance › Night reading. Three things happen.
Only the page changes. The window, sidebar and inspector keep whatever theme you use. The page turns from white paper to a dark grey sheet (not pure black, which makes text halo), and black text becomes a soft light grey.
Colours keep their hue. Instead of flipping colours, we change only how light or dark each one is, and leave the hue where it was. A red stamp stays red. Blue ink becomes a lighter blue that you can still read against the dark page. Yellow highlights stay yellow, a little deeper. Under the hood this is a lightness remap in a perceptual colour space called OKLab, applied to the page and its annotations together, so your own highlights and notes match the page.
Scans and photos are dimmed, not inverted. A page that is a single scanned or photographed image is never turned into a negative. It is dimmed to a little over half its brightness, with a slight warm cast, so a scanned letter reads like paper in lamplight.
One honest limit: on a page that is mostly text with a photo in it, the photo gets the same lightness remap as the text around it. It keeps its colours but looks dark and odd. If that photo matters, press ⇧⌘N to look at it as authored, then press it again.
Night reading is part of the free app.
What about a warmer screen?
Blue-ish white light feels harsher late in the evening, and many people find a warmer screen more comfortable. macOS already does this with Night Shift, in the Displays settings. Set it to run from sunset to sunrise and move the slider toward the warm end.
Night Shift and night reading work together: one changes the colour temperature of the whole display, the other changes how bright the page is. We did not build our own warm tint for the page, because Night Shift already covers every app at once and does it better than a filter inside one window could.
A note on the claims made for blue light: the evidence that it causes eye strain is weaker than the advertising suggests. What makes a difference is contrast with the room and how long you stare without a break.
What else helps your eyes?
Some plain things, in rough order of how much they help:
- Match the screen to the room. Turn the brightness down until the page is no brighter than a lit sheet of paper would be. A dim lamp behind the screen reduces the contrast too.
- Make the text bigger. ⌘+ zooms in, ⌘9 fits the page width. Squinting at a page set to fit the whole sheet in the window is tiring at any hour.
- Look away. The usual advice is every twenty minutes, at something across the room, for twenty seconds. It gets repeated because people do not do it.
- Turn whole pages instead of scrolling, if long reading sessions leave you tired. Single page view in the status bar, then ← and →.
Is an e-ink monitor better for night reading?
For long reading in a lit room, many people think so. An e-ink panel reflects light rather than shining it at you, so with a lamp on it reads like paper. It does not help in a fully dark room, because without a light there is nothing to reflect.
Better PDF has a separate E-ink mode for these screens, pure black on white with no motion and greys in four levels. Press ⌥⌘E for E-ink reading, which changes only the page. Night reading and E-ink reading are exclusive: turning one on turns the other off, since a dark page is the last thing an e-ink panel draws well. We wrote about it in Reading PDFs on E-ink, and why we built an E-ink mode, and the settings are in Help: Reading on an e-ink screen.
The shortcuts
| Shortcut | What it does |
|---|---|
| ⇧⌘N | Night reading on or off |
| ⌥⌘E | E-ink reading on or off |
| ⌘+ ⌘− | Zoom in, zoom out |
| ⌘9 | Fit the page width |
| ⌘0 | Actual size |
| ⌘F | Find in the document |
The rest of the reading shortcuts are in Open and read a PDF.
Night reading and E-ink reading are both in the free app. Better PDF needs macOS 26 or later; download it here.
Questions people ask
- Why is my PDF still white in dark mode?
- Dark mode changes the app's window, toolbars and sidebars, not the document. A PDF page is drawn as its author made it, which is almost always black on white.
- Is inverting colours bad for reading PDFs?
- For plain text it works well enough. For pages with photos, charts or coloured highlights it is poor, because photos become negatives and a red warning turns cyan.
- Does a warmer screen help with eye strain?
- A warmer screen, such as Night Shift on a Mac, is more comfortable in the evening for many people. The evidence that it prevents eye strain is thin, and screen brightness and breaks matter more.
- What is the shortcut for night reading in Better PDF?
- ⇧⌘N turns night reading on and off. ⌥⌘E switches to E-ink reading instead, and turning one on turns the other off.