[Harmless Teddy Bear]

What’s the difference between phone and book?

Blue light.

[BiglyCommentary]

Some smart phones have options to turn off blue light. I have that on auto after 7 pm.

[steve86]

I switch mine to night setting but then forget and it stays that way for several days. I can use either without problem. Don’t like automatic scheduling because one night I go to bed at 11:30, the next at 3:30 or 4 (like last night).