Here is a report on a survey of 25,000 IBMers. (By the way – I have no connection at all with IBM)

Flexible arrangements and the chance to work from your living room increases productivity so much that workers can carry on for 19 hours more than other employees before feeling any interference with family life.

The findings are based on a study of 24,436 employees of IBM, the technology company, across 75 different countries.

For office-based workers the tipping point at which staff felt that their working life started to interfere with their home life came after 38 hours of work a week.
However, for those offered a flexible working, including from home, the length of time that employees could worked without feeling the pressure was much longer.
On average they could put in 57 hours a week without feeling such a conflict.

The study “Finding an Extra Day or Two” is published in the Journal of Family Psychology. The research team, from Brigham Young University, in Salt Lake City, Utah, identified the point at which a quarter of employees the reported a conflict between work and family life.

Many of the home workers did spend some time working in an office, the study reports. But it was flexibility, including the option to do their job from other places, which allowed them to work for longer than other staff.

Prof E Jeffrey Hill, who led the study, said: “Telecommuting is really only beneficial for reducing work-life conflict when it is accompanied by flexitime.” Prof Hill, who once worked for IBM himself, said: “Managers were initially sceptical about the wisdom of working at home and said things like, ‘If we can’t see them, how can we know they are working?’” But now they are convinced of the benefits, he said.

His study also reports that eight in 10 IBM managers believe that flexible working increases productivity. “A down economy may actually give impetus to flexibility because most options save money or are cost-neutral,” he added. “Flexible work options are associated with higher job satisfaction, boosting morale when it may be suffering.”

More here:

‘Managers were initially sceptical about the wisdom of working at home and said things like ‘If we can’t see them, how can we know they are working?” Hill said.

Nowadays more than 80 percent of IBM managers agree that productivity increases in a flexible environment.

In the current economy, the scenario is being repeated with other businesses feeling the pinch.

‘A down economy may actually give impetus to flexibility because most options save money or are cost-neutral,’ Hill said. ‘Flexible work options are associated with higher job satisfaction, boosting morale when it may be suffering in a down economy.’

The study, titled ‘Finding an Extra Day or Two,’ will appear in the June issue of the Journal of Family Psychology. Study coauthors include BYU School of Family Life professors Jenet J. Erickson and Erin K. Holmes, and Maria Ferris, a retired IBM researcher.