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."

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.