MONDAY, Aug. 25, 2014 (HealthDay News) -- "Sleep drunkenness" is more common than previously thought, affecting about one in seven Americans, or 15 percent, according to a new study that looked at the sleeping habits of more than 19,000 adults.

Also called confusional arousal, the condition causes people to wake up in a confused state, not knowing where they are. In the most severe cases, they can injure themselves or others, explained lead researcher Dr. Maurice Ohayon, a professor of psychiatry at Stanford University School of Medicine.

"There was a case of a man on a ship who awoke in a confused state and fell off the deck to his death," Ohayon said.

In addition to such extreme cases, there have been cases where waking up in a confused state led to the person striking a bedmate. Most people can't remember the incident afterwards.

Ohayon noted that these episodes can occur even while taking a nap. "This happens to most people occasionally, like when you are jet-lagged," he said. The difference is that these episodes are frequent among those who suffer from confusional arousal, he noted.

Treatment for confusional arousal hinges on treating the other sleep problems patients have, Ohayon said. When these problems are treated, the condition often disappears.

Whether sleep drunkenness is its own condition or a symptom of other sleep problems is an ongoing debate, Ohayon noted.

The report was published in the Aug. 26 issue of the journal Neurology.

Dr. David Rye, a professor of neurology at Emory University in Atlanta, said, "Confusional arousals exist -- and are probably more common than we thought."

But, he added, "As in most epidemiological surveys, what is reported are associations, not causes and effects."

For the study, researchers interviewed more than 19,000 people aged 18 and older about their sleep habits and if they had experienced any symptoms of confusional arousal. They were also asked whether they had been diagnosed with a mental illness and about the medications they took.

The researchers found that 15 percent of the participants had a confusional arousal episode in the last year. Over half of those people said they had more than one episode per week.