How to dim non-jailbroken iPhone below dimmest factory setting?
Solution 1:
By definition, the software only allows certain brightness levels so only by modifying that software (jailbreak or perhaps Apple changes things) can you go dimmer.
There are many apps that use the colors and draw dimmer text (Instapaper uses black background at night and many stargazing apps only draw in red). You could try using the accessability features to invert the white / black system wide. Even though the screen is still as bright, the largely black screen will block most of the light from escaping. You can even set the triple press of the home button to toggle this rapidly.
Lastly, there are 3M polarized privacy screens (watch for vertical or horizontal privacy - most only work in one direction) to help solve the light escaping to your side issue.
If she is seeing the light reflect off of you, you're going to have to look for other options. Psychologically, most people can fall asleep with light, but light and motion or light and noise are much harder to sleep with. Hopefully it's just the light as you might just need to drop the phone or move to another location if it's not really the light that's the source of the irritation.
Solution 2:
If you find the minimum brightness still too bright for night-time reading, Apple has finally added a screen filter in iOS 8. Typically Android offered a way to reduce the minimum brightness via apps when the screen was still too bright for nighttime reading even when set to zero but now you can enable this in iOS:
- Go to Settings → General → Accessibility → Zoom.
- Enable Zoom.
- Triple-tap on the screen to bring up zoom options.
- Choose filter: low light.
- Go back to Settings → General → Accessibility → Zoom and change the zoom region to full screen.
- Turn Zoom off.
- Go to Settings → General → Accessibility → Accessibility Shortcut and set it to Zoom.
Now when you push your home button 3 times quickly it will dim the entire screen for night-time reading.