"There about 41 million workers who aren't getting the recommended amount of sleep," said Dr. Sara Luckhaupt, lead author of a new study from the division of surveillance, hazard evaluations and field studies at the National Institute for Occupational Safety and Health. The institute is part of the U.S. Centers for Disease Control and Prevention.
"Not surprisingly, workers who work the night shift are more likely to not get enough sleep," she said. Also, people who work more than one job or more than 40 hours a week are likely to get too little sleep, Luckhaupt said.
The National Sleep Foundation recommends that adults sleep seven to nine hours a night.
About 44 percent of night shift workers get too little sleep, compared to about 29 percent of people working the day shift. And certain industries take more of a toll on sleep than hours. Nearly 70 percent of those working night shifts in transportation and warehousing are sleep-deprived, the study said.
Working nights and sleeping during the day, in particular, disrupts the natural sleep cycle, called circadian rhythm, Luckhaupt said.
Workers who don't get enough sleep are more likely to get injured on the job and make mistakes that could injure them and their co-workers, according to the report.
Over time, insufficient sleep can also affect overall health, resulting in cardiovascular problems, obesity, diabetes and depression.
But there are way employers can help workers get enough sleep, Luckhaupt said, such as not starting shifts too early in the morning. If shifts rotate, it is better to go from an evening shift to a night shift than the other way around, she said.
Employers can also promote good sleep habits. These include going to sleep at the same time every day, having the bedroom quiet, dark and not too hot or too cold, and using the bed for sleep, not for reading or watching TV, Luckhaupt said.
For the report, published in the April 27 issue of the CDC's Morbidity and Mortality Weekly Report, researchers used data from the 2010 National Health Interview Survey to assess sleep habits of American workers.
Shelby Freedman Harris, director of the Behavioral Sleep Medicine Program and the Sleep-Wake Disorders Center at Montefiore Medical Center in New York City, said that "our society is a very sleep-deprived one."
The results are worrisome, he said, and include increased risk of heart attack, stroke, falls, car accidents, poor attention, depression, work absenteeism, irritability and weight gain.
"Despite these consequences, many people still don't find the time for adequate sleep, with many having trouble with insomnia and not seeking proper help," he added.
There are effective treatments to help with sleep issues arising from rotating shift work issues, but many people are unaware of them and many companies are not implementing them, Harris said.
For those working overnight shifts, strategically using bright light before and during work hours is helpful, along with dimming the lights at the end of the work period and wearing sunglasses on the drive home, he said.
For some workers, planning out a nap schedule is key. Others may require restructuring their sleep times at home, he added.
"I strongly encourage anyone who is struggling with adjusting to their shift to consult with a specialist. What is also important is making sure you have enough time between shifts to obtain a full night's sleep -- something many companies don't necessarily allow for," Harris said.
