Sexsomnia is a sleep disorder in which a person unknowingly enacts sexual behaviors whilst they're asleep. There is no cure for the condition, but medications and lifestyle changes have been shown to manage the disorder effectively.
It's thought that 7.1% of the global adult population will experience sexsomnia at some point in their lives, according to a 2018 review in the journal Cureus(opens in new tab). It's also thought to be more common in men than women, according to a 2007 paper in the journal Social Psychiatry and Psychiatric Epidemiology(opens in new tab), although it is unclear why.
Sexsomnia is sometimes called sleep sex, but it can involve all kinds of sexual behaviors including masturbation, moaning and orgasm. It can be distressing and embarrassing for both the person experiencing it and anyone sharing a room with them. Live Science spoke with experts to find out what is understood and what is still unknown about the disorder.
Sexsomnia is classed as a parasomnia, a group of disorders that includes sleep walking, sleep talking and night terrors. Parasomnias are grouped by sleep stage. Some occur during rapid-eye-movement (REM) sleep — "light" sleep in which our brain is active and dreaming — and some occur during deep, non-REM sleep.
Sexsomnia happens when the brain is suddenly, partially-aroused from deep, non-REM sleep, according to a 2010 report in the journal Clinical Neurology and Neurosurgery(opens in new tab). The person, still technically asleep, begins to enact certain sexual behaviors. Nearly all episodes are followed by amnesia, said Dr. Rexford Muza(opens in new tab), a sleep physician at Guy's and St Thomas' Hospital in the U.K.
During an episode, a person might fondle themselves or a bed partner, or they might make sexual noises or movements. Sexsomnia can involve sexual acts that the person has never done before or would never do when awake, Muza told Live Science.
A 2016 review led by Muza in the journal Current Opinion in Pulmonary Medicine(opens in new tab) found that women are more likely to masturbate during an episode, whilst men most frequently report initiating sexual intercourse with the person in the bed beside them. Sometimes the bed partner will be awake and consenting — though the person with sexsomnia is still asleep and won't remember in the morning. However, there have been cases in which neither party has been awake, which can have serious legal consequences.
Not much is understood about the mechanisms behind sexsomnia and other non-REM parasomnias.
Sleep studies can monitor the nightly brain activity of people who experience parasomnias using an electroencephalogram (EEG). According to a 2016 study in the journal Sleep(opens in new tab), in cases of sleepwalking and night terrors, which are also disorders of partial awakening like sexsomnia, EEG showed activity in the motor cortex and the cingulate cortex, the former being responsible for bodily movement and the latter for decision making. The rest of the brain still appeared soundly asleep.
But why would a partially awake brain enact sexual behaviors? Dr. Carlos Schenck(opens in new tab), a professor of psychiatry at the University of Minnesota Medical School, said disorders of partial awakening tend to involve one of our basic instincts.
"Eating, sex, walking, fear — all these basic instincts and primitive behaviors can be inappropriately released during sleep," he told Live Science. Why these particular behaviors occur in some individuals and not others isn't fully understood.
From cases of sexsomnia filmed in laboratory studies by Muza and his team, most are triggered by a bed partner moving. This stirring likely causes a partial arousal in the brain, he said, but anything that could disturb sleep — snoring, an external noise or sudden temperature change — could be a trigger.
People with obstructive sleep apnea — in which the throat muscles intermittently relax and block the airway during sleep — can get sexsomnia as a symptom, according to the Mayo Clinic(opens in new tab), as trouble breathing causes them to make gasping or choking noises in the night, partially waking up the brain.
Stress can also be a trigger. In one 2019 study, published in the journal Frontiers in Neurology(opens in new tab), 80% of participants with sleep-related motor behaviors found stressful situations could lead to more episodes, while a 2023 study in the journal Military Medicine(opens in new tab), which examined four individuals, suggested the stress of being on military duty may increase service members' risk for all non-REM parasomnias.
A high libido, however, is not a trigger for sexsomnia, Schenck said. "And there's no correlation between unsatisfied sexual drive and sexsomnia," he said.
