While most Americans say they're getting a good night's sleep, more than a quarter admit to dozing off at work, a recent employee survey shows.

In a nationwide survey of 1,000 employees in a variety of industries, 44 percent said they slept less than seven hours a night on workdays, according to the National Sleep Foundation, a Washington, D.C-based nonprofit organization. While 68 percent said they get enough sleep every night of the week, 32 percent said they sleep well only a few nights a month or less. Five percent said they suffered from severe sleepiness on a daily basis.

As a result, 29 percent reported falling asleep or nearly falling asleep at work during the past month, the survey found.

According to Sleep Foundation researchers, sleep deprivation can increase the risks of insomnia and other sleep disorders, while causing drowsiness at work. More than a quarter of survey respondents said a lack of sleep had interfered with their jobs a few times every month.

Still, most workers don't blame employers for their drowsiness. As many as 87 percent of survey respondents said their work schedules allowed sufficient time for sleep. In addition, about a third said their employers allowed naps during workplace breaks.