My one mad extravagance of the season was to buy everyone a Fitbit: initially just one, for the adults to share. Since we only went to the same places, it stood to reason that our step counts would be the same. While the synchronicity might account for the precipitous demise in our mutual civility (well, his; mine is still great), it didn’t work at all. Once he had a step-counter, I wanted one. Then the kids wanted one, which I normally would have found easy to resist, except I thought it may give us a fitness boost. We haven’t had much success in the Joe Wicks department lately. A sedentary lifestyle is the dream. I take it as a personal parenting triumph when they are not all supine.

Anyway, step-wise, the success has not been resounding. By far the best way of getting the male heir to up his activity levels is Pokémon Go and I didn’t even bother to buy him a Fitbit. The girls work full-time at subverting the system by working out what they can do instead of a step that the device will register as a step. Not many things, it turns out. This exercise is more intellectual than physical.

The sleep monitor, on the other hand, is genuinely fertile territory, as long as what you want to grow is unending conflict. It measures deep sleep, light and REM and gives you a score. You can, if you have no sense of privacy or human rights, sign in to your children’s accounts and plot what time they went to sleep against what time they said they went to sleep. The 10-year-old said it was like having an ankle tag under house arrest. The 12-year-old, in an act of magnificent strategic incompetence, lost her charger.

I, meanwhile, have peerless sleep scores, swinging like Tarzan from Good to Excellent. Everyone else thinks I should atone for my good fortune. But I just think it makes me the best.

• Zoe Williams is a Guardian columnist