Have you ever answered the phone in the morning to discover it was actually your alarm clock going off, or had a conversation in the middle of the night and woken up the next day with no recollection of it?
A new study suggests you are not alone. Researchers found many of us have had a similar experience in our lifetime.
The study, out Monday in the journal Neurology, says one in every seven people suffer from sleep "drunkenness" disorder, also called confusional arousal.
Confusional arousal is when a person wakes up and remains in a confused state for a certain period of time before either going back to sleep or fully waking up.
These episodes typically happen, according to the National Institutes of Health, when someone is awakened during non-rapid eye movement (REM) sleep, which is a deeper sleep period. And they're usually triggered by a forced awakening, like an alarm or phone call.
The study authors had more than 19,000 adults fill out a survey about their sleeping habits. They found 15.2% of the participants experienced one episode of confusional arousal during the past year.
Dr. Maurice Ohayon, lead study author and a sleep expert at Stanford University, was surprised by the substantial percentage. When he looked carefully, he says, he found over half of these participants have "confusional arousal one time or more a week, and that is considerable."
What's even more interesting, says Ohayon, is how long confusional arousal seems to last. While more than one third of the participants who experienced episodes once a week reported they lasted under 5 minutes, 32.3% of people said their episodes lasted between 5 and 15 minutes and 30% of people experienced episodes lasting 15 minutes or more.
If someone is experiencing these episodes, they need to let their doctors know, says Ohayon. An episode can cause violent behavior during sleep, according to the study.
"You can hurt yourself physically, hurt someone (else). You wake up irritable and possibly violent." He compares it to waking up in a hotel room - you don't know where you are or what hour it is, so your reaction or responses to the environment are not adapted.
Ohayon says shift workers, such as doctors or pilots, who nap during work and can be awakened suddenly, should block at least 15 minutes of time for their bodies to truly wake up before, say, taking command of a plane or making life-or-death decisions.
The study found that 84% of those with sleep drunkenness disorder also had another sleep disorder, a mental health disorder or were taking psychotropic drugs such as antidepressants. Less than 1% of the people with sleep drunkenness had no known cause or related condition.
Dr. David Alexander Schulman, director of the sleep lab at Emory University in Atlanta, says having these episodes isn't uncommon. "Fifteen percent sounds shocking," but when you think about it, most of us have had these type experiences.
One of the things that can make confusion arousal worse is sleep deprivation. Schulman says it's well known that American's don't sleep enough. "If you are getting less than 6 hours a night, and you are having confusional arousal, then the first thing you need to do is try getting more sleep," he says.
Schulman was skeptical of the number of participants whose episodes lasted more than 15 minutes. While he says these episodes can be common and often funny, most people don't continue to talk into the phone for 15 minutes when their alarm clock is going off.
"I'd be surprised if the episode lasted more than 15 minutes," he said. "That's one of the struggles with a subjective survey."