“Among the creative professions, it’s very, very common,” says comedy producer and performer John Lloyd, who made the TV series QI and Blackadder.

“There’s a very, very high incidence of bipolar disorder. It’s because stable people think the world’s fine as it is. They don’t see any particular need to change it.

"Creative people don’t feel like that. People who want to change the world tend to suffer a lot for it.”

The novelist Robin Sloan offers a wise middle way, borrowing a concept from share trading, which he applies to writing, but which seems relevant for many modern careers. Think about your work, he suggests, as divided into “stock” and “flow”. Flow is day-to-day, high-visibility stuff: putting yourself out there, networking at conferences, Twitter and LinkedIn, reminding the world you exist. Stock is substantive, long-term work that lasts – in Sloan’s case, his books. “I feel like we all got really good at flow, really fast,” he writes. “But flow is ephemeral. Stock sticks around. Stock is capital. Stock is protein.”