Furthermore, the increased risk of injury and illness associated with putting in a lot of overtime has nothing to do with how hazardous a job is, the authors say.

Culture of Long Work Hours

The research team evaluated the responses of almost 11,000 Americans to the annual National Longitudinal Survey of Youth. The survey asked about employment history, work schedules and sick leave during the period between 1987 and 2000.

In their analysis of 110,236 job records, the researchers noted 5,139 work-related injuries and illnesses. More than half were associated with jobs requiring extended working hours or overtime. In the United States, up to a third of overtime is compulsory.

After adjusting for age, gender, type of industry and job, the team found that employees working overtime were 61% more likely to sustain a work-related injury or illness than employees who did not work overtime.

Length of Commute Irrelevant

Working at least 12 hours a day was associated with a 37% increased risk of injury or illness, while working at least 60 hours a week was associated with a 23% increased risk, compared with those who worked fewer hours.

The more hours worked, the greater was the risk. Interestingly, lengthy commutes had no impact on the injury/illness rate.

Further analysis indicated that the increased risks were not merely the result of demanding work schedules being concentrated in inherently "riskier" industries or jobs.

These findings back up the theory that long working hours indirectly precipitate workplace accidents by inducing fatigue and stress, the authors conclude. They support government initiatives, such as those espoused by the European Union, to cut working hours in the US.