Haruto Sanjo

His argument is that circadian rhythm responds to light timing far more reliably than it responds to willpower or bedtime intentions. Most morning-routine advice fails, in his account, because it tries to fix wake-up behavior directly instead of fixing the one input the body actually reads: when bright light hits the eyes. Once the anchor hour is stable for a few weeks, waking up stops requiring effort because the body starts anticipating it.

He is explicit about what breaks this system: weekend sleep-ins longer than about an hour past the anchor, and evening light (screens, overhead lighting) that confuses the same mechanism in reverse. He treats a single blown weekend as a two-to-three-day setback, not a catastrophe — the fix is just returning to the anchor the next available morning, not punishing the lapse.

Rather than demanding a full routine overhaul, he recommends picking the anchor hour first, doing nothing else differently for two weeks, and only then layering in additional morning structure. In his account, people who try to change ten things at once quit within a week; people who fix the one light-timing variable tend to stick with it because the payoff (easier waking) shows up almost immediately.

He pairs the morning anchor with a matching evening light cutoff — dimming overhead lights and avoiding bright screens for the last hour before the target bedtime — arguing that the two ends of the day are one system, not two separate habits to maintain.