A new study has explored a sleep disorder called "sleep drunkenness", which affects one in every seven people and causes episodes of waking up confused.
According to the study, the disorder involves confusion or inappropriate behavior, such as answering the phone instead of turning off the alarm, during or following arousals from sleep, either during the first part of the night or in the morning. An episode, often triggered by a forced awakening, may even cause violent behavior during sleep or amnesia of the episode.
Study author Maurice M Ohayon said that these episodes of waking up confused have received considerably less attention than sleepwalking even though the consequences can be just as serious.
The researchers asked 19,136 people age 18 and older from the general US population about their sleep habits and whether they had experienced any symptoms of the disorder and about mental illness diagnoses and any medications they took.
The findings show that 15 percent of the group had experienced an episode in the last year, with more than half reporting more than one episode per week.
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While in the majority of cases 84% people with sleep drunkenness also had a sleep disorder, a mental health disorder or were taking psychotropic drugs such as antidepressants and less than 1% of the people with sleep drunkenness had no known cause or related condition.
The research also found that about 31% of people with sleep drunkenness were taking psychotropic medications such as antidepressants. Both long and short sleep times were associated with the sleep disorder. About 20% of those getting less than six hours of sleep per night and 15% of those getting at least nine hours experienced sleep drunkenness. People with sleep apnea also were more likely to have the disorder.
The study was published in the medical journal of the American Academy of Neurology.