"A serious job costs this"

There's a version of the habit that's a matter of pride. You're not someone who leaves at five and forgets. You care. The job is serious and you take it seriously, and a serious job comes home with you. If the family gets a little less of you on a Tuesday, that's the price of being the kind of person who does the work properly, and they knew that about you.

The earlier book The work will still be there took apart the belief that hours measure commitment. This chapter is about the same belief applied to the head rather than the clock. And the research on detachment is inconvenient for it. Sabine Sonnentag and colleagues followed 309 people in demanding service jobs for a year. High demands predicted exhaustion a year later, as you'd expect. But the people who switched off in the evenings were not the ones whose commitment faded. They were the ones who stayed engaged with their work. Among the people under the heaviest load, the ones who left it at work were protected against the fall in engagement that the others showed. The passenger wasn't the sign of caring. It was what wore the caring away.

I want to be fair to the objection, because there's something in it. Wendsche and Lohmann-Haislah's pooled analysis found that detachment went with better performance on the core tasks of the job, but slightly worse performance on the extras, the going beyond the role, and slightly lower creativity. Those links were small, and they came from surveys that can't say what caused what. But I'd rather report them than pretend. It's possible that some of what you produce comes from a head that never fully leaves. The question is whether it's worth what it costs, and whether it's coming from the fret, which produces nothing, or the working-out, which chapter 12 gives its own place.

Most of what a serious job actually needs from you is done between nine and half past five with a clear head. The clear head is what the evening is for. A person who arrives on Wednesday having spent Tuesday night at the desk arrives with Tuesday still in them. Sonnentag and Bayer's diary study found that on the days people did detach, they reported less fatigue, and the effect was biggest on the highest-pressure days. That's the serious job's own argument for leaving it behind. The harder the day, the more the next day needs you to have had an evening.

And the leftovers aren't a price the family agreed to. They agreed to you. What they get instead, on the evenings the passenger rides along, is a body at the table and a person somewhere else, and they didn't sign anything that said so.