I was going to write about doing puzzles before I read the article, Energize Your Brain: Ways To Keep Your Brain Energized, Happy, and Active. Seems I was thinking along the right lines even though my suggestion for you leaned more toward the fun of it all, but if the bonus to doing puzzles is brain exercising, all the better brighter easier! (I couldn't resist that one :))
Whether you enjoy Sudoku, Cryptoquotes (AKA Cryptograms), Crosswords, Scrambles, Acrostics or any other puzzle that makes you think, try putting the phone down and using a good, old-fashioned pencil! It is much easier on the eyes, and you can make notes in the margins, which is very helpful when you are Sudoku Kookoo and need to keep track of your deductive reasoning!
Whatever way you do them, keep it up, and if you're addicted to Candy Crush and haven't seen a crossword in years, consider finding a good puzzle book to add to your beach bag, your commuter tote, or at your bedside. Your brain and phone battery will thank you!
PS Be sure to spray a little ROOMIGATOR™ on your pillow if you are puzzling before sleep. The lavender essential oil will help you relax.