updated 6/8/2010 2:05:01 PM ET 2010-06-08T18:05:01

If you feel yourself nodding off during a meeting today, rest assured that you're not the only one. Nearly one in five Americans who participated in a recent study reported falling asleep or being drowsy in situations that required a high level of concentration, such as during meetings or conversations.

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And excessive sleepiness is more common in the U.S. than in Europe, the study found. This raises concerns for public health and safety, according to research that will be presented today at the annual meeting of the Associated Professional Sleep Societies LLC in San Antonio, Texas.

Sleep studies are prone to concluding that we're all sleep-deprived. Often, as is the case with this one, they're funded by drug companies that benefit from this perception. In fact, scientists aren't really sure how much sleep you need, and studies find that the requirement varies significantly from one person to another, for reasons not fully understood.

So what's most interesting in the new study is not so much the idea that many people aren't getting enough sleep, but that Americans suffer the problem more than do Europeans.

The researchers found that 19.5 percent of U.S. adults reported having moderate to excessive sleepiness, and the results were comparable between men and women. In a previous study, researchers reported that the prevalence of excessive daytime sleepiness in five European countries was 15 percent.

Further, 11 percent of U.S. participants reported severe sleepiness, which was more prevalent in women(13 percent) than in men (8.6 percent).

“The prevalence of excessive daytime sleepiness is very high in the American population, much higher than what we observed in the European population,” said principal investigator Dr. Maurice Ohayon, psychiatry professor at Stanford University and director of the Stanford Sleep Epidemiology Research Center in Palo Alto, Calif.

“Insufficient sleep is plaguing the American population and is one of the leading factors for excessive daytime sleepiness,” Ohayon said.

Who's at risk
People with obstructive sleep apnea were three times more likely to be sleepy during the daytime, people with insomnia and those who typically sleep for six hours or less were more than two times more likely to be drowsy, and people who perform night work and those with a major depressive disorder were nearly two times more likely to report sleepiness.

These results raise public safety concerns, particularly regarding the potential for workplace injuries and drowsy driving accidents related to excessive sleepiness.

“The number of individuals sleepy or drowsy during situations where they should be alert is disturbing,” Ohayon said. “Sleepiness is underestimated in its daily life consequences for the general population, for the shift workers and for the people reducing their amount of sleep for any kind of good reasons. It is always a mistake to curtail your sleep.”

Last October the CDC released survey data showing that about 11 percent of respondents reported that they never got enough rest or sleep during the past 30 days.

The new study involved a sample of 8,937 people aged 18 or over living in Texas, New York and California. Participants were interviewed by telephone on sleeping habits, health, sleep problems and mental disorders. The research was supported by the Arrillaga Foundation, the National Institute of Neurological Disorders and Stroke of the National Institutes of Health, and an educational grant from Cephalon, a pharmaceutical company.

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