Light, dark, and bedtime

Most bedtime advice starts too late, at the pillow, with a tea. Your evening started at the overhead LEDs, the late email, and the idea that one more episode is how adults relax. Light is information. Dark is information. Bedtime is the appointment those two keep.

The short version

Bright day. Dim night. A cooler, darker room. Caffeine has a closing time. Alcohol can knock you out and still fragment the night.

A how-to for the house you already have

Morning. Get outdoor light within an hour of waking if you can. A short walk counts. It sets the timestamp for the clock described in Circadian rhythm as a foundation.

Afternoon. Caffeine lingers for hours and does not care about your meeting. Choose a last-coffee hour and treat it as a sleep decision.

Evening. Dim the house an hour before you want to be asleep. Lamps beat ceiling grids. Phones can go dimmer and warmer, and they can also live in another room. If the phone is your alarm, you still do not need the feed.

The room. Cooler than the rest of the house if you can manage it. Darker than you think. Quieter than a documentary about sleep. Partners who snore, children who wake, and cities that never stop are real; earplugs and blackout curtains are unglamorous tools that work.

The last inputs. A huge late meal asks digestion to work the night shift. A fight by text is a cortisol bedtime story.

If you are already late

Keep tomorrow's morning light. Sleep what the night allows, get a little sky, and return to your window the next evening. Weekend catch-up sleep can help a debt; it works poorly as the only plan. See Prevention.

When lamps are beside the point

Loud snoring, witnessed pauses in breathing, dozing off while driving, or sleepiness that feels like weather belong with a clinician. So does a night that is mostly pain. Depression rewrites nights too. Set up the room anyway, then get help for what the room cannot fix.

Light, dark, bedtime. Change only those three for a month and you will have run a real experiment.