Working at a startup is a bit like being a medical student – you clock in long hours, abandon your social life and dedicate yourself with single-mindedness to surviving those first few painful years. That’s how a lot of startups succeed. But maybe there’s another path.

Eschewing the traditional model of the 80-hour or even 100-hour work week, a new renegade crop of companies is turning the idea of work-life balance on its head. A small but growing number of these businesses across America are challenging the conventional wisdom that slavish dedication to long hours is required for entrepreneurial success.

Borrowing from the French work model, technology startups from Silicon Valley to New Jersey are implementing shorter but more intensive and, perhaps, more efficient work weeks in an effort to increase productivity and permit their employees to establish a better work-life balance, while meeting the needs of demanding customers.

“The sheer amount of work we complete is astounding,” said Sonja Rasula, the founder and CEO of UniqueLA, a large market selling local goods. She’s a staunch advocate of the four-day work week. “My employees are well-rested and actively enjoy ‘time off,’ which results in higher productivity during those four workdays and an increased happiness level.”

Rasula’s employees clock eight hours a day, Monday through Thursday. Fridays are reserved for leisure and personal time, which Rasula believes makes her employees perform better. “My staff are ‘out there’ more, like going to museums, reading books, seeing movies, eating at new restaurants, which means we actually know what is happening in the streets to understand and predict trends long before the masses know about them.”

A recent study from the Families and Work Institute found that flexibility in when and where employees work is on the rise, particularly in small companies, defined as employing between 55 and 99 people. Small companies were more likely than large companies (1000 or more employees) to offer their workers more flexible hours, the study found.

Proponents of a shorter work week say it makes intuitive as well as business sense. Employers report their employees are more dedicated when they’re on the job because they value the extra time that they have off to pursue other interests.

Matthew Davis, vice president and operations manager at RevPart, a rapid prototyping manufacturer for plastic parts, was wary at first about offering employees fewer hours. But the company hired someone for a test run of the 30-hour week, offering her the same health care and other benefits given to staff members who work 40 hours.

To his surprise, Davis said: “Something really great happened – she is so productive we cannot get her enough work.”

Most countries have shorter work weeks than the US, according to the Organisation for Economic Cooperation and Development. Twenty-two of its 34 member countries work fewer than 40 hours per week. According to a 2014 Gallup poll, half of all US full-time employees say they work more than 40 hours a week, while nearly four in 10 say they clock in more than 50 hours.

The notion of a shorter work week isn’t new, and in fact was seen as the ideal before the middle part of the 20th century, says Benjamin Hunnicutt, a professor of leisure studies at the University of Iowa and the author of Free Time: the Forgotten American Dream. The more that technology and industry advanced, conventional wisdom went, it would be possible to work less. And indeed, after the Great Depression, working hours did generally decrease.

Hunnicutt argues that in recent years a fetish of work for work’s sake has overtaken the 19th-century hope of work being a means to an end. Hunnicutt says Americans have a “religion of work, a modern fetish, work for more work, wealth for more wealth”.

Interestingly, though, extra desk time doesn’t always translate to more work product. According to a recent study from Stanford University, productivity typically drops after 50 hours of work, and someone who works 70 hours gets no more done than one who works 55 hours.

“In our experience, the shortening of the work week has increased our productivity and morale within our small company,” said Greg Chan, founder of the Hydro Carbon Group, a six-person startup based in Utah.

When Chan founded the company in 2012, he and his colleagues regularly put in 60 to 80 hours a week, including Saturdays, but found they weren’t getting as much accomplished as they would have liked. In fact, it was quite the opposite. “People were working more hours and thus spreading their workload over those hours, reducing productivity,” Chan said. “Morale went down.”

Not everybody agrees with the 30-hour week. Angelo Kinicki, a professor at the WP Carey School of Business at Arizona State University and an expert in organizational culture, says a shorter week is an unrealistic model for a startup because of the sheer amount of work that needs to get done. “While working long hours can erode job satisfaction, the thrill of working in a startup can typically overcome any negativity associated with work hours,” he said.

On the other hand, some startups go a step further by offering “total flexibility,” says Tomar Galzberg, a self-described “growth hacking consultant” who helps startups and small businesses attract more customers.

“One of my contracts is at a startup with no restrictions on work hours,” he said. “They have staff that work 9 to 5, and staff that work remotely from home, in transit and internationally, with no questions asked.”

Some work cultures, in the meantime, evolve as startups grow. When Koby Kasnett founded e-commerce repricer Appeagle three years ago, a shorter work week wasn’t a priority. But Kasnett soon realized his 22 employees needed more work-life balance, so he implemented a policy of half-day Fridays every week.

Employee satisfaction and productivity – at least on Fridays – shot up, he said. “We believe in autonomy. Someone doesn’t need to put in 80-plus hours a week in the office to prove they’re doing their job.”