Get a Lower Brightness
Looking at your smartphone late at night isn’t recommended. Even with Night Shift enabled and the device set to a lower brightness, the screen can still be too bright for your eyes to handle in dim environments. Luckily, there’s a hidden feature in Accessibility that can help.
Go to Settings > General > Accessibility and select Zoom. Enable Zoom, and change Zoom Region to Full-Screen Zoom and Zoom Filter to Low Light. From there, just exit back to the Home screen and triple-tap the display with three fingers. Select Zoom Out. Now, the iPhone’s display should be less bright than even the dimmest native setting.