A charitable foundation employing 800 people has shelved a proposed trial of a four-day working week.
The Wellcome Trust, a medical research charity based in central London, said in January that reducing the working week by a day was one of a "few ideas" being analysed.
It suggested the move could boost productivity and staff wellbeing - but has now said it would prove "too operationally complex to implement".
Ed Whiting, Wellcome's director of policy, said: "After extensive internal consultation on whether we should trial the four-day week, we have concluded that it is too operationally complex to implement.
"We have learnt a lot through our consultation process and, although we not be trialling a four-day week, we remain committed to maximising the impact Wellcome can make in the world through supporting the wellbeing and productivity of our staff."
The Trades Union Congress has previously said moves should be made to cut the working week to four days over the course of this century.
Earlier this year, a study was published that argued people should work a maximum of 32 hours a week and get paid for five days' work.
"At the New Economics Foundation we have long called for a shorter working week to tackle many of the societal problems we face – from gender inequality to overwork and stress," Alice Martin, head of Work and Pay at the New Economics Foundation wrote in the report for New Scientist.
Their report suggested that working long hours – between 50 to 60 per week – is bad for mental and physical health.
Research from the Australian National University showed that people can work for 40 hours a week before it has a damaging effect on their mental health.
