The brightness of the screens of these smartphones is enough to make you cross eyed if you are not careful. I recently purchased the Motorola Moto G5 Plus and one of the very first apps I installed was an app called Twilight. What Twilight does is this:
The Twilight app makes your device screen adapt to the time of the day. It filters the flux of blue light emitted by your phone or tablet after sunset and protects your eyes with a soft and pleasant red filter. The filter intensity is smoothly adjusted to the sun cycle based on your local sunset and sunrise times.
I especially like using Twilight prior to bedtime and when I am driving at night (when using my map and music apps). Believe it or not (and I believe this), research suggests that exposure to blue light before sleep may distort your natural (circadian) rhythm and cause inability to fall asleep. With Twilight the screen turns to a redish tint; which, believe it or not makes your eyes feel more relaxed. Twilight can be configured to activate automatically or manually. In my case, I have it set to the manual setting so that I can toggle it on and off at will. Twilight is a FREE app with no advertisements and is highly rated and sought after in the Google Play Store.
SOURCE: Google Play – Twilight