Dripping with sweat and awash in disco lights, they dance away to pulsating club music at Lunch Beat, a trend that started in Stockholm and is spreading to other cites in Europe.
Then they go back to work.
"It is absolutely fantastic!" exclaimed Asa Andersson, 33, who broke away from her job at a coffee shop to bust some moves last week. "It is the first time I'm here, I'm totally happy and ecstatic, totally covered in sweat and I'm full of energy. It does not get any better than this."
The first Lunch Beat was held in June 2010 in an underground parking lot in Stockholm. Only 14 people showed up. But they had so much fun they immediately planned another event. Word spread, and now the Swedish capital has monthly Lunch Beats that attract hundreds.
Similar events have been held in at least 10 other Swedish cities and in Finland and Serbia. Portugal's first try will be in Porto next month, organizers said.
The party starts at noon and goes on for one hour. There's no alcohol, which gives it a different ambiance than nighttime clubbing, said Daniel Odelstad, the 31-year-old organizer of Lunch Beat Stockholm.
"People are sober, it's in the middle of the day and it is very short, effective and intensive," he said. "You just have to get in there and dance because the hour ends pretty quickly."
Heeding that advice, nearly 500 people paid 100 kronor ($14) to attend at Kulturhuset, a cultural centre in downtown Stockholm.
Anyone can organize a Lunch Beat event as long as they follow some simple rules, Odelstad said.
"The first rule of Lunch Beat is that you have to dance," he said while checking prepaid tickets at the door. "If you don't want to dance during your lunch hour, then you should eat your lunch somewhere else."
The events are not-for-profit, with cover charges being used for rent and sandwiches so dancers don't return to work hungry.
Some first-time visitors were amazed at how quickly typically reserved Swedes burst out of their shells. As the DJ pumped up the base, office clerks mingled with business-suit types, the young mixed it up with the middle-aged and university students danced with everyone.
"It was just like bang, straight in to the disco," said Kristoffer Svenberg, a 34-year-old artist.
But isn't it uncomfortable returning to an office after an hour of dancing? European workers, a tad more relaxed than Americans, say no.
Ellen Bengtsson, 29, came to Lunch Beat with more than a dozen people from a government office.
"It's great," she said. "We'll go back sweaty together."