Switching off isn’t just a preference — it’s about how your body works, and knowing the mechanics makes the case better than any amount of encouragement.

Lesson 3 showed the mechanism: recovery happens when your body’s stress systems stand down after the day, and an evening spent mentally at work keeps them running.⁶ This lesson is about where that cost actually shows up.

It lands hardest on sleep. Take work worries to bed and the sleeping brain stays measurably more alert — you take longer to fall asleep, wake more often, and get less deep sleep.¹⁴ Across studies, more detachment goes with better sleep (r ≈ .30) and less physical discomfort.¹⁰

One honest limit, because this program also tells you what the evidence doesn’t show: direct proof that detaching lowers stress hormones or blood pressure is thin — a handful of small studies with no clear effect (r ≈ .03, not significant, from three studies).¹⁰ So we won’t tell you that switching off lowers your cortisol. The real, demonstrated gains are in sleep and in how you feel — which is where you’d actually notice them.

Why does the sleep finding matter so much? Because sleep is where the recovery half of Lesson 3 mostly happens. If work follows you to bed, your main repair mechanism runs degraded. Tomorrow starts lower. The day costs more. And there’s more to chew over tomorrow night.

That’s the loop at its meanest, because each turn causes the next and none of the steps look unreasonable. Nobody decides to lie awake rehearsing a conversation. It’s simply what a stress system that hasn’t stood down does with a quiet room.

This also explains a specific frustration. If you’ve been doing everything right on sleep — same bedtime, no screens, dark room — and you’re still lying there, the sleep advice wasn’t wrong. It was aimed at the wrong thing. The arousal arriving at bedtime was generated hours earlier, and no amount of bedroom hygiene reaches something that started at six o’clock.

That’s the loop this unit breaks. It’s why the boundary work is aimed at the evening specifically, not at your attitude to work in general.

One thing to be clear about. If sleep is your dominant problem — not “work keeps me up” but genuine, months-long insomnia that was there before this job and would be there without it — then the sleep program in this app is the better one to run. It’s a full course on exactly that, and it will do more for that shape of problem than boundary work will.