Lack of sleep catches up with today's workforce

— -- U.S. workers are silently suffering from a dramatic lack of sleep, costing companies billions of dollars in lost productivity, says a study out Monday.

Nearly three in 10 workers have become very sleepy, or even fallen asleep, at work in the past month, according to a first-ever study on sleep and the workplace by the non-profit National Sleep Foundation. The late-2007 survey was based on a random sample of 1,000 workers.

"It's a very expensive issue for employers, and it can be fatal, too," says Nilesh Dave, medical director of the Sleep and Breathing Disorders Center at the University of Texas Southwestern Medical Center in Dallas. "The 24/7 global economy means work is now around the clock."

About 70 million Americans have a problem sleeping, according to the NSF. Some employers, such as Union Pacific unp railroad, are so concerned that they're now allowing workers to nap on the job. Employees also say it's a significant issue, causing them to drive drowsy or even fall asleep at their desks.

Ursula Forhan, 53, of Chicago, used to fall asleep at her desk. She was treated for sleep apnea and says she has no problems today.

"I would take a nap on the floor of my office, and my boss was so tolerant he would step over me," says Forhan, a paralegal in Chicago. She used to drive for work and had to roll down the windows to stay awake.

Among the survey's findings:

•Dangers on the road. Thirty-six percent of respondents say they have nodded off or fallen asleep while driving, including 26% who say they drive drowsy during the workday.

•Work performance. Twelve percent of respondents have arrived late to work in the past month because of sleepiness. Other problems cited: impatience with others, difficulty concentrating on job tasks and lower productivity.

•Work hours. Employees with more than one job report the highest rate of dissatisfaction with sleep: 43% say they get a good night's sleep only a few nights per month or less. Part-time workers report the highest rate of sleep satisfaction.

Several factors are driving the trend toward sleepier employees. Employees are putting in longer hours, in part due to increased pressure from employers to ramp up productivity. The study found that one-fourth of respondents have a workday that lasts between eight and nine hours, and another fourth say they work up to 10 hours a day.

Technology, which is supposed to enhance productivity, has also required employees to be available. "You're not disconnecting except when you hit the pillow," says Mark Rosekind, a consultant who worked on the survey.

TELL US: How has your sleep affected your performance at work? Have you ever fallen asleep on the job?