You never know who you might meet in the wee, small hours of an all-night diner.

Here’s a Navy man celebrating his last night in New York City with friends before being deployed. Over there is a tipsy rock singer executing a perfect run-through of Michael Jackson’s dance moves to “Thriller.” And in comes a 60-year-old intensive-care-unit nurse and her wife, sitting down to a romantic dinner after a long night of clubbing.

There’s a chaotic cadence to the 24-hour diner — a refuge where patrons of all ages, backgrounds and tastes are welcome to bump elbows over patty melts and pancakes. Unlike the restaurant that keeps traditional business hours, the diner shape-shifts as the night wears on and different kinds of customers pour in. It can be whatever they need it to be — its menu, mood and playlist often changing from hour to hour.

All-night diners are a signature New York institution. But in a city that supposedly never sleeps, they’re disappearing as costs rise, food delivery booms and many citizens keep the earlier-to-bed schedules they developed during the pandemic. According to Yelp data, the city lost 13 percent of its more than 500 round-the-clock restaurants from February 2020 to January 2024, including favorites like Neptune Diner in Astoria, Queens, and Arch Diner near Canarsie Pier in Brooklyn.

In the midst of all those closings, at least one place was reborn: Kellogg’s Diner, a stalwart of Williamsburg, Brooklyn, from 1928. It returned in September after a half-year hiatus, with new ownership, a refurbished interior, a slightly fancier menu by the chef Jackie Carnesi — and two months later, 24-hour service.

“It was a niche that needed to be filled,” Ms. Carnesi said. “Post-pandemic, the number of 24-hour restaurants that ceased to exist left a big hole in the heart of New York City.”