The night out started with New York’s literati and ended with a fog machine.

It was something of a typical Wednesday for Emily Witt, who knows how to float between worlds. As a staff writer for The New Yorker, she writes about abortion, climate change and, recently, Kamala Harris’s presidential campaign. As a techno enthusiast, she spends her evenings going to raves, subsumed into a cathartic microcosm of New York’s nightlife, which she describes with clinical neutrality in her new memoir, “Health and Safety: A Breakdown.”

“The misconception that having fun is for young people, that there’s an expiration date, I don’t totally understand,” Ms. Witt, 43, said.

Early that night, at a party hosted by The Paris Review at its office in Chelsea, she looked a little uneasy.

“This is a professional space,” said Ms. Witt, who was wearing a long black coat over a sheer tank top and dark purple shorts. “Whereas, in the other, no one knows what anyone does for work.”

She snaked through the room in search of Emily Stokes, the magazine’s editor and an old friend and mentor of Ms. Witt’s. After a few minutes, Ms. Stokes appeared from the crowd. The two embraced, and Ms. Witt seemed to relax.