Insomnia is one of the quietest health epidemics in America. Most people drag themselves through a full day of work and/or school on a limited amount of sleep, creating or worsening internal and external health problems in people. Even more importantly to corporations, the lack of sleep might hurt productivity, which we all should know by now is the main reason this study was funded so heavily.

Researchers surveyed 7,428 employed people across the U.S. and found that 23% experienced some form of insomnia — such as difficulty falling asleep or nighttime waking — at least three times a week during the previous month, for at least 30 minutes at a stretch.

Not surprisingly, these sleep problems carried over into the workplace. Insomniacs were no more likely than their well-rested peers to miss work, but they were so consistently tired on the job that they cost their employers the equivalent of 7.8 days of work in lost productivity each year—an amount equal to an average of about $2,280 in salary per person.

Keeping up with the theme of humans as cattle, researchers estimated that these human “beasts of burden” cost corporations 63 billion dollars in lost productivity.

Just like a loyal lap-dog or plow-horse, most study participants did not physically miss work due to insomnia, says lead author Ronald Kessler, Ph.D., a psychiatric epidemiologist at Harvard Medical School, in Boston.

“Employers these days want their workers to stay home if they’re sick. If they know you’re absent, they can at least find ways to fill in for you,” Kessler says. “But you can’t stay home every day if you’re chronically sleep deprived, so these people get in the habit of going to work and then not performing.”

About one-third of all U.S. adults experience weekly difficulties with nighttime sleep, and an estimated 50 to 70 million people complain of associated daytime impairment, the study notes.

Kessler’s study, published today in the journal Sleep, is an outgrowth of the American Insomnia Survey, a research project led by the World Health Organization (WHO) and Harvard Medical School that began in 2008.  According to Health.com the study was funded by large corporations:

The survey and new study were funded, respectively, by Sanofi-Aventis (the maker of Ambien) and Merck, which is developing a new insomnia drug currently in the final phase of clinical trials.