That Friday feeling could soon be switched to Thursday, at one major employer at least. The Wellcome Trust is considering moving all of its 800 head office staff to a four-day week in a bid to boost productivity and improve work-life balance.

A trial of the new working week at the £26bn London-based science research foundation could start as soon as this autumn, giving workers Fridays off to do whatever they want with no reduction in pay. Some parts of the organisation already operate a no-emails policy in the evenings or at weekends, but this would mark a more dramatic change.

It is believed the Wellcome Trust would become the biggest organisation anywhere in the world to try a four-day week. The idea comes amid arguments from trade unions that the fruits of advances in computer technology and artificial intelligence, which improve productivity, should be shared among workers by changing to a shorter working week.

Wellcome’s idea means that by the time everyone else’s weekend has started, its employees could have spent a day volunteering, studying another skill or spending time with loved ones.

The Trades Unions Congress (TUC) last year called for a wholesale reduction of working hoursin the UK, citing research that found almost half of workers want a four-day week. It said UK workers put in the longest hours in the EU, behind only Austria and Greece. In 1930, the economist John Maynard Keynes predicted a 15-hour working week for his generation’s grandchildren but the TUC found more than 1.4 million people were working seven days a week.

The presenter Kirsty Wark has also called for the switch, saying the extra day off should be used to develop “another skill, do yoga, get fit, or look after a relative”. She said: “I think it takes a radical shift to change our living for the weekend culture.”

Wellcome, which is the world’s second-biggest research donor after the Bill and Melinda Gates Foundation, has been looking closely at last year’s decision by the New Zealand insurance company Perpetual Guardian to switch to a four-day working week.

“It looks like moving the working week to four days rather than five gets you a broader productivity and wellbeing benefit,” said Ed Whiting, Wellcome’s director of policy. “You have a healthier workforce, a reduction in sickness absence and improved sense of work-life balance.”

He said analysis of the impact of Perpetual Guardian’s switch in March and April, which involved 240 staff, showed small increases in total output, despite staff working shorter hours.

A study by the University of Auckland showed 78% of employees felt better able to successfully manage their work-life balance, an increase of 24% compared with the five-day week, and stress levels decreased by 7% across the board. Workers’ sense of stimulation, commitment and empowerment all improved significantly, with overall life satisfaction increasing by 5%.

Workers felt less “psychologically rushed” and had more time to get things done at home, which in turn boosted their motivation at work.

The presenter Kirsty Wark: ‘I think it takes a radical shift to change our living for the weekend culture.’ Photograph: James Gourley/Rex/Shutterstock

Wellcome said it was still gathering evidence and would make a final decision in the coming months. An autumn trial could involve all or just part of the head office workforce in London.

“If you have a shorter working week you have to think how can you use your time really effectively,” said Whiting, who used to work as an adviser to David Cameron in Downing Street. “It’s the concept of seeing time as the most finite thing.”

“You have less slacker time in your day,” he added. As a result, people tend to better prioritise their work.

However, the Auckland study also found increased stress among some people at having to complete tasks in a shorter timeframe. Some managers reported some workers took the extra day off “as a gift” and did not become more efficient.

Surveys have suggested office workers have the capacity to spend hours procrastinating every day. One found only one-fifth of people felt they were consistently productive, with the top distractions cited as checking social media, reading news websites and chatting with colleagues about non-work matters.

Wellcome has not entirely settled on the idea of the four-day week and said it was also considering other options for boosting productivity and improving work-life balance, including more flexible working hours. It said it wanted to hear from more organisations that have tried the switch to a four-day week and those that have considered the move but decided against it.

Potential risks it has identified include a loss of flexibility if people are required to work only Monday to Thursday. There is also the risk of a public-facing organisation, which handles £1bn a year in science funding, being perceived to make the move as a luxury rather than to increase productivity and wellbeing.

The core of the organisation’s work is processing and assessing grant applications for scientific research across biology, medicine, population health, the humanities and social science. That is the kind of predictable process that might be well suited to a shorter week, it believes. It is still working out whether skeleton staffs or rotas are needed to maintain cover in other areas of the organisation.

“[The question is] would we make a greater impact on the world with a four-day week?” said Whiting. “That looks like a very appealing proposition.”