You don’t actually need to keep your phone screen on for Pokémon Sleep, although you’ll risk the app closing in the background and recording a shorter sleep session.
The first time you play Pokémon Sleep, the sleep-tracking, Pokémon-catching mobile game, you’ll be prompted to leave your phone screen on but to just put your phone face down on the bed. That said, you’ll need to keep your phone plugged in as well, or else you risk your phone battery dying overnight.
(For context, I’m using an iPhone 13 that has seen better days to play Pokémon Sleep, so my experiences may be the same as those who use an Android or a newer iPhone.)
The plus side is that flipping your phone over will dim the screen, though it won’t actually lock your phone. The screen will stay on, and while it’s mostly replaced by black space, you’ll still see the time, service provider information, and battery indicators at the top of your display. Obviously, people (myself included) are apprehensive about leaving their phone screens on overnight.
The other option, as stated by the game, is to invest in the Pokémon Go Plus Plus, a little gadget that will track your sleep for you, instead of your phone.
The Go Plus Plus costs $55.
