The Four-Day Workweek Trials: What the Evidence Actually Shows

In 2022, 61 companies in the UK cut the working week for about 2,900 employees, kept their pay the same, and watched what happened for six months. When the trial ended, 56 of them said they were keeping the shorter week.

That is a striking result. It is also one study among several, and the details behind it matter if you run a small team.

What the Trials Tested

The biggest recent study came out in 2025 in the journal Nature Human Behaviour. Researchers followed 2,896 employees at 141 organizations across Australia, Canada, Ireland, New Zealand, the UK and the US. Companies reduced working time for six months, most often to a four-day week, and reorganized how work got done before the trial started. A control group of 285 employees came from companies that had shown interest but didn’t take part.

Employees in the trial reported less burnout, higher job satisfaction and better mental and physical health. The control group didn’t see those changes. The researchers tied the gains to three things: people felt more able to do their work, they slept better and they were less fatigued. The bigger the cut in hours, the bigger the improvement.

The Trials Before It

The 2025 paper builds on earlier work.

The UK pilot (2022). Run by researchers at Boston College and Cambridge with 4 Day Week Global, the 4 Day Week Campaign and Autonomy, it covered those 61 companies and roughly 2,900 employees. About 71% of employees reported lower burnout, and 92% of the companies kept the shorter week afterward.

Iceland (2015–2019). More than 2,500 workers, about 1% of the country’s workforce, moved from 40 hours to 35 or 36 with no cut in pay. The trials ran through Reykjavik City Council and the national government. Productivity stayed the same or improved at most workplaces, and stress and burnout fell. Today about 86% of Iceland’s workforce either works shorter hours or has the right to ask for them.

Microsoft Japan (2019). The company gave employees five Fridays off in a row, and reported sales per employee up about 40% compared to the same month the year before. That is one month, one company and one comparison, so I treat it as an interesting data point and nothing more.

What the Evidence Can’t Tell You

This is the part that rarely makes the headlines.

Companies chose to take part, and they signed up through an advocacy organization. The authors of the 2025 paper say so themselves, noting the results likely overestimate the true effect. Every outcome in that study was self-reported, and the researchers collected no productivity or revenue data.

The sample also skews toward people with desk jobs. About 46% worked in professional services, 73% were college-educated and most worked remotely or in a hybrid setup, in English-speaking, high-income countries. The trial lasted six months, with a 12-month follow-up.

What’s mostly missing is evidence from businesses where someone has to be on site or answer the phone five days a week. If your crew runs on coverage and customer deadlines, these trials don’t answer your question yet. They tell you that burnout can come down when a company reorganizes its work first. They don’t tell you how to fit a shorter week around a schedule full of appointments.

Brandon’s Take

I spent most of my career in corporate America, where the hours are long and most companies don’t care about employee burnout. The mentality is simple: if someone burns out, you find a replacement. I’ve seen how that plays out, and I built my company to work differently.

At Intelligent Analytics, I make sure work is scoped appropriately, and that the time it takes is shared with the client up front. That’s how my team and I avoid long hours. Generally, no one is logged in after noon on Fridays. Work-life balance is extremely important to me and to this company.

I also know I have an advantage most service businesses don’t. I don’t have to be on site for my work. When a client needs an after-hours meeting, we still do it, and then we make the time up somewhere else. Friday afternoons are a no-work zone, and if someone takes a late meeting, the team flexes their time later in the week.

I’m a firm believer in paying someone what they’re worth, not how many hours they sit at a desk. The 40-hour, five-day week is an arbitrary number made up a long time ago, and I don’t think it holds up. If a project is scoped and planned properly, you work the project. A company should know, or be able to find out, how long a project, task or service takes. You’re paying your employees and contractors for their knowledge and experience, and for doing the job right and above expectations. You aren’t paying for hours.

I would recommend a four-day week, or at least Friday afternoons off, to just about everyone. I understand it’s harder for a small, owner-operated service business. So here are two smaller versions:

• One Friday afternoon a month. Block it on the calendar and treat it as a real day off.
• Staggered schedules. Put some of your team on Monday through Thursday and the rest on Tuesday through Friday. You still cover five business days, and each person works four.

For anyone thinking about this, my advice is to start with your services. Know how long each service, project or task takes. Then tell your customers and schedule accordingly. And don’t be afraid to turn work away. Everyone worries about losing business, but keeping experienced people is worth more than saying yes to every client who calls, and burning out the team to do it.

Shorter weeks aren’t a perk I hand out. They follow from planning the work properly, and I’d rather plan well and keep good people.

Frequently Asked Questions

Did the trials keep pay the same?

In the UK pilot and in Iceland, yes. Employees worked fewer hours at the same pay, and that was a condition of taking part. Keep that in mind when you read the results, because most small businesses can’t copy that arrangement without changing how they price and scope their work.

Does a four-day week lower productivity?

Most of the trials report that productivity held steady or improved, but much of that data comes from the companies themselves. The 2025 study measured how employees felt and collected no productivity numbers. So the honest answer is that it looks promising, and it hasn’t been proven for every kind of business.

Can a small service business try this?

There’s little research on frontline, coverage-driven work, but there are ways to try it carefully. A single Friday afternoon off each month costs very little to test. Staggered schedules keep all five days covered while each person works four.

How do I know if my team can handle a shorter week?

Start by measuring. If you know how long each of your services takes, you can tell whether the work fits into fewer hours, and you can give customers realistic timelines. If you don’t have that data yet, collecting it is the first step.

Sources

• Fan et al., Nature Human Behaviour (2025): Four-day week trial
• Research Live: UK four-day week trial results
• IZA World of Labor: Iceland trial
• soon.works: What the four-day week trials measured
• Fox 29: Microsoft Japan’s four-day week