A new study suggests that occupational safety is influenced to a large degree by what workers do – or don’t do – before ever coming in to work.

Researchers at Harvard Medical School in Boston surveyed more than 10,000 people in the U.S. and found that that insomnia is responsible for 274,000 workplace accidents and errors each year, adding up to $31 billion in extra costs.

Study participants who reported having insomnia said they caused accidents or made errors at work that cost at least $500, such as getting into a vehicular accident while on the job, or causing an assembly line to be shut down.

While the research isn’t conclusive, and depends upon recollections, it does suggest a connection between lack of sleep and workplace errors and accidents.

The findings could encourage workplaces to pay more attention to insomnia and screen employees for the condition, said lead author Victoria Shahly, a clinical psychologist and instructor at Harvard Medical School in Boston.

"Accidents and errors directly affect the corporate bottom line," Shahly said.

It is unknown if the study participants who suffered from sleeplessness had a worse memory about workplace accidents than those who didn't. It also is not clear how much it would cost to treat an estimated 20 percent of the working population of the United States for insomnia and whether the expense would run to more than the cost of the workplace errors themselves.

Kevin Morgan, director of Loughborough University's Clinical Sleep Research Unit, in Leicestershire, England, said the study is important because it covers on an "under-researched" topic.

Previous efforts to understand the effect of sleeplessness on work have looked at how it causes employees to stay home from their jobs, instead of focusing on what happens when sleepy employees go to work.

Morgan said that treating insomnia is tricky, and runs the risk of creating workers who are dependent on prescription sleep remedies.

A more promising – and inexpensive -- treatment is cognitive behavioral therapy designed to help change the way people think, Morgan said. Approximately 60 percent to 70 percent of long-term insomniacs can get a benefit from four to five hours of cognitive behavioral therapy.

The study appears in the October issue of the journal Archives of General Psychiatry.