“The first thing he did,” Priya Sundaram says, “was tell me to spend less time in bed. I thought he’d misheard me.”

The first six weeks changed nothing about the medication. They were spent, instead, watching — a reading logged every few minutes and a diary that took about forty seconds a day to keep.

Three patterns emerged, and none of them were the ones anyone expected. The obvious suspect turned out to be innocent; the quiet one had been doing the damage for years.

Week two is the worst week. We tell everybody that in week one, because otherwise they leave in week two.

Illustrative composite

Progress was not linear. There was a plateau around week nineteen that felt, at the time, like the programme had stopped working. It had not.

“I stopped treating a bad night as a catastrophe. That’s the whole trick, and it took eight weeks to learn.”