Trying to attract and retain workers? Forget pizza parties and nap pods. Companies in the U.K. are looking at a more promising solution: the four-day work week.

"Visits to our recruitment page have gone up by 60% and enquiries to the company have gone up by 534%," Helen Brittain, human resources director at environmental consultancy Tyler Grange, told CNBC's Make It.

The company is among those taking part in the U.K.'s trial for a four-day work week. Since implementing a shorter working week, the firm has noticed a huge difference when it comes to recruitment and retainment of employees.

"The interest that people are showing in the company is amazing," Brittain said.

Tyler Grange isn't the only company that has noticed a difference. Gaming-focused communications consultancy The Story Mob is another one, according to its founder and co-CEO Anna Rozwandowicz.

"We have definitely seen an increase in interest from job seekers," she said, adding that shortly after shifting to the four-day work week, the team was able to fill a position that had been vacant for a long time.

Britain's four-day work week trial is the largest of its kind so far, and has had widely positive reactions from employees and companies taking part. The idea behind it is simple: Workers aim for the same levels of productivity and output in 20% less time, for 100% of their pay.

The 4 Day Week Global campaign has also started a trial in Australia and New Zealand and is planning to expand in the United States, Canada, Europe and South Africa throughout 2022 and 2023.

Recruiting in an employee's market

For education technology firm Bedrock Learning, making recruitment and retention easier was a key driver for shifting to a four-day work week.

"Being brutally honest, it is a retention and recruitment piece," its CEO and founder Aaron Leary told CNBC's Make It. "It has been very much an employee's market through the pandemic and there's been a lot of movement, a lot of changing and Bedrock was also sort of susceptible to that," he added.

Like many other companies, Bedrock Learning struggled with the Great Resignation and the shift to flexible working, which made maintaining a company culture more difficult while making it easier to switch jobs. In early 2022, job vacancies also hit an all-time high in the U.K., according to the country's Office for National Statistics, increasing competition for workers and therefore making recruitment harder.

Marketing agency Loud Mouth Media, also part of the four-day work week trial, was also affected. "That's why we got involved," said Managing Director Mark Haslam.

"During Covid our guys were just getting tapped up, left, right and centre," he says, adding that competition for talent also intensified as companies started adding new perks for employees.

The shift to the four-day work week has been game changing for both companies.

"I would say things have completely sort of stabilised compared to what they were in terms of like retention," Bedrock Learning's Leary said, adding that only one employee has resigned since June, when the trial began.  

Over at Loud Mouth Media, Haslam also noticed major changes in both recruitment and retention.

"I would say our applications have doubled. We get a lot more ad hoc applications," he said. "Our retention of staff went up from 80% to 98%."

More applications = better candidates?

However, the surge in applications doesn't necessarily make it any easier to find the right candidate, Haslam said.

"If somebody comes to me and says I want to work for you because you do a four-day week, we don't entertain them remotely. Because it's not a genuine driver for somebody and that just means somebody wants to work less, you know, it makes you kind of question their ethics," he says.

Haslam said he wants to hire candidates who are aligned with the company's values and goals, and that goes beyond the four-day week.

Tyler Grange has had similar experiences.

"We get an awful lot of people apply because we're a four-day week trial company and not because they've got the right skill that we would actually be looking for in our business," said Human Resources Director Brittain.

The firm's managing director Simon Ursell agrees. "There aren't that many applicants that are applying specifically for the roles we want," he said. Even with the four-day work week, it remains difficult to fill some roles and find suitable candidates as the job market remains tough, he added.

"So, it's not the panacea."