What the screen does
Bright, blue-heavy light in the evening delays the release of melatonin, the hormone that signals night to the body. The stronger effect is mental. Feeds, short videos, games and work email keep the brain alert and, unlike a book chapter or a television episode, never reach an end. The pattern even has a name, bedtime procrastination, in which a day with no free time gets paid back at midnight out of the sleep budget. Adults need at least seven hours a night, and the first thing a phone in bed takes is the first hour.
Evening rules that work
- Set a fixed screens-off time 30 to 60 minutes before you intend to sleep, and let the phone enforce it with a scheduled sleep or do-not-disturb mode that permits calls only from a short list of people.
- Charge the phone in the kitchen or hallway, and use a separate alarm clock, which removes the most common excuse.
- Turn on the warm-color night setting from sunset and dim the screen. It helps a little, and it does not make scrolling in bed harmless.
- Put a daily limit on the two or three apps that swallow your late hours, and have someone else set the override code.
- Fill the gap with something that ends, such as a paper book, a shower or tomorrow's list written by hand.
The three in the morning problem
Checking the time on a phone in the middle of the night delivers light, a row of notifications and a small shot of arithmetic about how little sleep is left. Keep the phone out of reach. If you have been awake for about twenty minutes, get up and do something dull in dim light until you are sleepy, instead of reaching for the screen.
Measure it
The screen-time report on your phone shows hours per app, the number of pickups and the time of the first pickup each day. Look at the hours after ten at night for one week before you change anything. The figure tells you which single app to limit. Get outside in daylight within an hour of waking, which sets the body clock more strongly than any screen setting. Trouble sleeping that lasts more than a few weeks, screens or no screens, is worth raising with a doctor.
Tip If the phone has to stay in the bedroom because you are on call or a caregiver, put it face down across the room with only the sounds you truly need allowed through.
