In the late 1990s, Clint Greenleaf was working 18-hour days as an accountant at Deloitte & Touche -- a company he was drawn to by its reputation for a progressive work-life balance policy.

What he found instead were strung-out employees taking catnaps at their desks.

"You're working way too hard, and it was never expected that you'd be tired, or get sick," says Greenleaf. "Most of the time, you're kind of there, but you're not." Feeling bored and miserable, he quit after just seven months.

Today, at the helm of Greenleaf Books, an Austin, Texas-based independent-press publishing company he launched in 1997, Greenleaf makes sure all 25 of his employees know they can go home when they're too sleepy -- or come in late, or take the whole day off. "As long as they get the job done, it's fine," says Greenleaf, 31. As a result, staffers are generally well-rested and alert most of the time, he says -- though with seven pregnancies among them in less than a year, including his own baby daughter born just weeks ago, they can expect more than a few sleepless nights ahead.   

Yet whether it's the result of overwork or a crying baby at home, sleep deprivation isn't just an employee's problem. Gone untreated, studies show, a sleepy workforce can cut into productivity, raise the risk of workplace injuries, and lower employee job satisfaction, among other problems.

What's certain is that much of the U.S. labor force is dog tired. Up to 70 million Americans suffer from insomnia and wakefulness, according to a recent report by the Institute of Medicine, a Washington-based medical research group. That's a lot, considering that up to 20 percent of serious car crashes are attributed to sleepy drivers, or that sleeping less than five hours a night nearly doubles your risk of suffering a heart attack, or that twenty-somethings who sleep less than six hours a night are 7.5 times more likely to be overweight.

In the business world, a restless night is the most common reason cited when employees are late for work, according to the National Sleep Federation, a Washington-based non-profit group that seeks to raise awareness of sleep disorders. Even among punctual workers, three in 10 admit to making critical on-the-job mistakes as a result of chronic fatigue, the group says.

All told, sleepy workers are costing U.S. employers up to $136.4 billion a year in lost productivity, according to researchers at Caremark, a Nashville, Tenn.-based pharmaceutical services firm. Untreated, sleeping problems can develop into serious illnesses or depression, costing employers more than $1,000 in added health-care expenses, a separate study found.

Beyond lost productivity and added health-care costs, sleep disorders can simply cast a pall over staff morale. Last year, University of Florida researchers tracked the sleeping habits of 45 employees at a local insurance firm over a period of three weeks. Employees who slept well, they found, were far more satisfied with their jobs than those who tossed and turned all night. "There are so many things that can impact the way you feel about your job," says Brent Scott, a graduate student in management who led the study. “It's interesting that something as simple as a good night's sleep can make a big difference.”

Scott says sleepy employees are more likely to be hostile toward co-workers, feel less interested in their work, and can become a serious drain on staff morale. All of that can be avoided, he says, by allowing workers to recharge their batteries with flex-hours, or even flex-days. "It can be as simple as allowing employees to have a short break. I mean, whatever happened to breaks?" asks Scott. Far from offering breaks, many employers use e-mail, cell phones, and Blackberries to keep staffers on call around the clock.

To raise awareness of the hazards of sleep deprivation, the Sleep Disorders Center of Columbus Regional Hospital in Columbus, Ind., recently began offering local employers on-site training sessions in getting a good night's sleep. The so-called "Sleep Updates," led by sleep specialists, are geared to groups of 10 or more employees, offering risk assessment tests, information on sleep disorders, and a sleep diary to help identify potential problems.    

"We have certified sleep doctors go out to the factories and warehouses in our community," says Rita Deskins, the center's coordinator.

There, they try to spread the word about the importance of exercise and a regular nighttime routine in inducing a restful sleep. They discourage alcohol, caffeine, heavy meals, and vigorous workouts right before bed.

It's one of only a handful of similar workplace programs available across the nation.

Luckily for its own workers, the center also practices what it preaches. Deskins has long allowed her employees to choose shifts that best fit their home-life routines, and even bought a light box for overnight staff -- tricking their natural sleep cycles into recalibrating day for night. "We want them to be able to feel rested, refreshed, and ready to do a good job," he says.