Staying mentally available outside work hours feels like it protects your performance, evidence you are still on top of things, still committed. Research on recovery from work found close to the opposite is true, and the belief itself is worth examining directly rather than treated as obviously correct.
The four things that actually help you recover
Sabine Sonnentag, a researcher at the University of Mannheim, studies what actually helps people recover from work stress. Her research identifies four recovery experiences, psychological detachment, relaxation, control, and mastery, and finds detachment, genuinely not thinking about work during non work time, the most consistently important of the four.
Employees who detach more from work during evenings and weekends report fewer strain symptoms and higher life satisfaction. That part is about as well evidenced as anything in this literature. Detachment is one of the few reliable things standing between sustained demand and exhaustion.
It is not free, though, and the same meta-analytic work says so plainly. Detachment carries a small negative relationship with contextual performance, around minus point one three, and with creativity, around minus point one one. The discretionary extras — the unasked-for help, the idea that arrives sideways on a Sunday — do come partly from a mind still turning the work over.
So there is a real trade, and it is still worth making. A small cost to the extras, against a large and well established protection from exhaustion. Anyone selling you switching off as free is not describing the evidence.
The belief this actually contradicts
The specific belief driving this is that staying mentally engaged during off hours, thinking about a problem, half watching for messages, is what keeps performance high. That belief treats time not spent on work as time lost. The larger pattern runs the other way, time genuinely spent not thinking about work is what allows the version of you that shows up the next day to actually function well.
This is not a claim that visible availability never matters in any workplace, some roles and some managers genuinely expect it, and that is a separate, structural question this does not resolve. It is a claim about what happens inside your own head once the visible part is accounted for.
Where to start
Pick one specific window, a weekday evening, a Saturday morning, something concrete rather than a vague resolution to work less. During that window, treat not thinking about work as a deliberate input into how you function afterward, not a lapse in discipline or a sign you care less.
Notice what changes about the following day, not just how the evening felt.
Whether your specific workplace can actually support a real window, or whether the visible availability question needs solving first, is something you will judge better than any general finding can. What this gives you is a reason to protect the window on its own merits, not just as a nice to have.
There is a specific way to signal that a window is protected without it reading as disengagement to the people around you, and it is worth working out before you need to defend it.