"I can't help it, it's just there"

You may believe you're simply built this way. Some people can walk out of the office and be somewhere else by the car park. You're not one of them, and never have been, and there's no point pretending an evening routine will change what kind of head you've got.

The research doesn't support that picture. The ability to stop thinking about work after hours has a name in the literature, psychological detachment, and the same person has more of it on some days than others. Sabine Sonnentag and Ute-Vera Bayer followed 87 people in a range of jobs across three working days and found that how much detachment someone managed in the evening depended on the day. Heavier workload, less detachment. On days when people did manage it, they reported a better mood and less fatigue, and the fatigue link was strongest on days of high time pressure, which is to say the days it's hardest. If detachment were a fixed trait, it wouldn't move with Tuesday's workload. It moves.

A meta-analysis by Johannes Wendsche and Andrea Lohmann-Haislah pooled 91 samples and more than 38,000 employees. Job demands were linked to less detachment. So was what they called heavy work investment, which is roughly how much of yourself you put in. Doing work-related things in your own time was linked to it too, at a medium size. Age and gender weren't. Those are all things about the job and about how you're working it, not a temperament you were born with. And a temperament wouldn't respond to training.

It responds to training. Verena Hahn and colleagues gave 48 people two sessions a week apart on how to recover from work, and compared them with 47 on a waiting list. Detachment and the other recovery experiences were higher a week after the training and still higher three weeks after. Sleep quality was up. Perceived stress was down at three weeks. It was a small study and it didn't shift exhaustion, so I don't want to oversell it. But two sessions moved something that was supposedly fixed.

A meta-analysis by Tina Karabinski and colleagues pulled together 30 studies of interventions meant to improve detachment, with 3,725 people, and found an average effect that researchers would call small to moderate. Longer and more intensive programmes did more. The programmes worked better for older people and for people who were already struggling with recovery, which is to say people like the one reading this chapter.

None of that means you can decide at the roundabout not to think about work and have it happen. It means the passenger isn't a fact about your head. It's a fact about your day, and about what you do in the last ten minutes of it, and about what's waiting for you at home to occupy the space. Those can be changed, and the rest of this book is about changing them.