Charge the phone in another room overnight. Not face down, not on the far side of the bed: another room, so that reaching it means standing up.

What the research says

Measurement work in habit research supports automaticity, how little thought a routine takes, rather than sheer repetition, as the ingredient that makes a routine hold. Dropping the phone on a shelf as you pass it every night is exactly the kind of fixed, cue driven step that measure was built to describe. That work is about how habits are measured, not about sleep or attention, so the sleep benefit here is sensible reasoning rather than a finding.

Strength of evidence: one line of research. A single study, or a theoretical account.