Screen & dim-light curfew
Melanopic (blue-enriched) light late in the evening suppresses melatonin and pushes circadian phase later. Counting back from bedtime gives practical tiers: reduce stimulation, then warm / dim only, then screens off.
Bed target: 22:30
3 h before bed
19:30
Start lowering brightness and blue: Night Shift / f.lux / warm desk lamp; avoid overhead cool LEDs. Prefer paper or audio if you can.
1 h before bed
21:30
Room lights dim; phones/tablets lowest brightness, extra warm, avoid scrolling in bed.
30 min before bed
22:00
Screens off or across the room on grayscale — cue the brain that sleep is next.
Educational estimates only. Sleep and caffeine metabolism vary widely. This is not medical advice; talk to a clinician if you have insomnia, apnea, or other conditions.