After college, most people do their best to avoid having to pull any more all-nighters. But for some, even after graduation, the wee hours of the morning are the most productive.

That is what led Amber Lambke and Allan Grinshtein to start a group called the New York Nightowls, a sort of study hall for entrepreneurs, freelancers and software developers who gather at 10 every Thursday night and stay as late as 4 a.m…

“If it fits in with their lifestyle, it can work very well,” he said. “A large part of their waking day is when things are quieting down.”

The popularity of the Nightowls idea suggests that there are plenty of people in this camp. Johan Hedberg, a 33-year-old public relations consultant in Stockholm, became interested in coordinating a local version after he saw an online posting about the group. “I have a lot of friends and colleagues writing books and working on Web projects who sit by themselves at home,” he said. “There is so much more to gain by working with other people.”