Jeff Archibald, designer and co-founder of Paper Leaf in Edmonton, Alta., poses for a photo on Friday June 26, 2015. As managers Jeff and his wife Andrea work to ensure staffers prioritize their work and don't get overbooked to help avoid burnout. THE CANADIAN PRESS/Jason Franson

TORONTO - Whether it's to help boost their paycheques, complete a project or satisfy their workaholic spirit, some employees think little of logging extra hours on the job.

But experts say significant stretches of overtime without adequate time for recovery could not only result in diminished work performance, but it could also pose potentially serious health risks.

A University of Massachusetts study published by the journal Occupational and Environmental Medicine in 2005 explored the impact of overtime and long work hours on occupational injuries and illness.

Researchers cited studies associating overtime and extended work schedules with heightened risk of hypertension, cardiovascular disease, fatigue, stress, depression, chronic infections, diabetes and death.

They also noted some studies found evidence of links between long working hours and an increased risk of occupational injuries, including among construction workers, nurses, miners, bus drivers and firefighters.

"While some occupations have restrictions on length of work shift, most don't," said Dr. Cameron Mustard, president and senior scientist at the Institute for Work & Health in Toronto.

"Whether you're in a health-care facility, a manufacturing facility, driving a vehicle, if you're tired, the risks of mistakes are going to go up."

Two studies comparing eight- and 12-hour schedules during day and night shifts found that 12-hour night shifts were associated with more physical fatigue, smoking or alcohol use, according to a 2004 report from the U.S. Centers for Disease Control and Prevention.

"It's the law of diminishing returns," said Liane Davey, vice-president of team solutions with Lee Hecht Harrison Knightsbridge, which specializes in talent recruitment and development.

"We think that we're staying and doing more and being more productive; but the negative outcome of doing that actually means that our core quality suffers."

Irregular schedules — like switching from a block of night shifts to day shifts — can result in sleep disturbance which can become chronic, noted Mustard.

"If you build up a period of disturbed sleep ... this is somewhat different from fatigue, although in a sense the consequence is kind of the same.

"If we can't rest, we're not renewing our cognitive and physical capacities."

German-born Moritz Erhardt was a week from completing a work placement at Bank of America Merrill Lynch in London when he died in 2013. A British coroner said the 21-year-old intern died of an epileptic seizure that may have been triggered by fatigue.

Erhardt's case sparked widespread speculation that the notorious long working hours and competitive environment at top investment banks were to blame for his death.

Matt Ferguson said his 22-year-old brother Andy died in a head-on collision in 2011 after logging excessive hours as an unpaid intern at an Edmonton radio station. Proposed amendments to the Canada Labour Code set to come into effect include requiring employers to keep records of the number of hours worked by interns.

When Jeff and Andrea Archibald launched their design agency, the couple initially worked from home and logged significant extra time to establish their business.

"We definitely hit 60-hour work weeks mainly because when there's two of you, you have to do all the billable work," recalled Jeff.

"When you're starting out, your rate's a little lower, and then you have to balance out with all the business side of things, like invoicing. You don't have anybody on staff that can do those kinds of things, so you're basically wearing all of the hats.

"What ends up happening is you have all your meetings and your phone calls ... during the day and you do your production work at night — and that's not just us. A lot of our friends are in similar situations."

The Archibalds are now part of a team of seven at their Edmonton-based custom web and branding firm Paper Leaf. Weekly meetings help assess key tasks to accomplish within a given day and week — and avoid overbooking.

"One of the singularly biggest concerns I think we all have is balancing the amount of workload so that we can have a profitable company — but also not overworking people," Jeff said.

"When you overwork, you're staring down the barrel of burnout. It's a real short-term gain."

Mustard said employees logging overtime should be aware of the pace of their work and ensure they are taking breaks.

"Being thoughtful about nutrition, making sure that you're not missing meals is very important. And then rest. Not shortening your chance to have sleep."

— With files from The Associated Press.

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News from © The Canadian Press, 2015