When I ask Schneeberg what went into her rating system, she says each option’s blue light output plays a part. (She asks clients to use the night mode on their devices , if they must use them before bed.) But just as impactful was the type of pastime. Specifically, she considers, “Are you using each device in an interactive way, or in a passive way?” Reading or watching a video is going to be less likely to keep you awake than publishing pictures, liking posts, or reading and responding to emails, she notes. “Interactivity keeps you more stimulated and less shut down.” It helps to imagine that your phone has become a book or movie player at bedtime, she suggests.