Sleep drunkenness is a real thing and it could affect as many as one in seven Americans, a study reports.

The disorder is more formally known as confusion arousal. It occurs when a person wakes up from a deep sleep in a state of confusion and doesn't remember the experience later. Sometimes this can lead to inappropriate behavior.

The paper, published in Neurology, explains the research conducted by Dr. Maurice Ohayon from Stanford School of Medicine in more detail. In the study, researchers interviewed more than 19,000 Americans about their sleep habits and possible confusion arousal.

Confusion arousal is not to be confused with night terrors or sleepwalking and is often seen in children. It has not previously been studied with much detail in adults.  

Researchers found that approximately 15 percent of people surveyed reported at least one episode of sleep drunkenness in the past year and just over half of those people said they had at least one episode per week. An additional 25 percent of people reported five episodes per month.

The duration of sleep drunkenness episodes averaged less than five minutes for a third of participants, five to 15 minutes for another third and more than 15 minutes for the rest of the study subjects.

"It's like they are totally drunk - they don't know where they are or what they're doing," Ohayon said.

Most of the people who had an episode of confusion arousal could attribute the episode to something such as a mental disorder. Of the people who had confusion arousal episodes, 70 percent had sleep disorders and 37 percent had a mental illnesses. Only 31 percent of those with mental illnesses or sleep disorders were taking medication - mostly antidepressants.

Getting too much sleep or too little sleep can lead to sleep drunkenness as well. Researchers found that 20 percent of people who got less than six hours of sleep and 15 percent of those who reported getting more than nine hours of sleep a night reported having an episode of confusion arousal.

Researchers did find, however, that 0.9 percent of the sample reported episodes that could not be attributed to something else.They also found that use of sleep aids such as zolpidem (Ambien) was not related to episodes of sleep drunkennes.