Introduction
Sexsomnia, also known as sleep sex or somnambulistic sexual behavior, refers to unintentional sexual behaviors or activities during sleep. Sexsomnia is a relatively new diagnosis. The term was coined by Shapiro and colleagues in 2003,[1] but cases of this condition have been reported in the literature for the past 3 decades.[2,3]
Sexual behavior during sleep automatism can range from explicit vocalizations to touching or sexual intercourse, and in some cases even sexual assault or rape. It is non-rapid eye movement (NREM) parasomnia characterized by abnormal transitions between sleep and wake states. The second edition of the International Classification of Sleep Disorders (ICSD-2) discusses somnambulistic sexual activity in the context of disorders of arousal from NREM sleep.[4]
Most commonly, NREM parasomnias arise from slow-wave sleep (SWS). Because of a relative lack of cortical control, partial arousals from this deep state of sleep can lead to uninhibited manifestations of primal drives. In this way, sexsomnia is linked to other primal drives. For example, fear and anger may manifest as night terrors, whereas hunger and thirst manifest as nocturnal eating or drinking.
Clinical Presentation and Associated Conditions
Slow-wave parasomnias, such as sexsomnia, typically occur during the first few hours of sleep. Like other SWS parasomnias, patients are unaware of the events, and they have no conscious interactions with their surroundings. Even if patients awaken during the event, they typically have no recollection of what is happening.
Most SWS parasomnias that present in childhood resolve before adolescence, but occasionally they continue into adulthood. It is uncommon for primary parasomnias to present initially in adulthood.
Persons with sexsomnia frequently have other parasomnias, such as sleepwalking, confusional arousals, night terrors, or nocturnal binge eating. Sexsomnia is thought to be a variant of sleepwalking, because a considerable majority of persons with sexsomnia also have a personal or family history of somnambulism.
Factors that cause sleep fragmentation may precipitate this type of parasomnia in susceptible adults. Most commonly, these factors include stress, untreated sleep apnea, alcohol, sleep deprivation, and medications (particularly serotonergic antidepressants).[5]
Differential Diagnosis
REM sleep behavior disorder (RBD) is a rare condition in which patients physically act out their dreams. During normal REM sleep, we experience loss of muscle tone and activity. Persons with RBD do not experience this skeletal muscle inhibition and can engage in dream-enacting behavior. These events are typically brief and limited. However, they can also be associated with complex motor activity.
Unlike SWS parasomnias, RBD usually occurs towards the end of the night and patients often recall the events, frequently explaining that they knew they were acting out the dream. They will awaken easily and readily interact with their surroundings.
RBD is most commonly reported in men in their 60s and 70s, and there is a strong association with progressive neurologic degenerative disorders, such as Parkinson disease.[6] Serotonergic medications can also increase the risk for RBD behavior.[7]
It may be difficult to differentiate malingering or willful sexual assault from sexsomnia. A careful history and physical examination to identify risk factors are vital, particularly when the sexsomnia behavior involves legal issue. Interviewing family members to further clarify the details of childhood parasomnias or similar prior events is often required. In many cases, polysomnography is helpful, but patients may not always experience classic events in the sleep laboratory.
Legal Implications
Recent cases from England[8] and Canada [9]are examples of a growing number of acquittals resulting from a sexsomnia defense. Those who argue against this stance claim that people who know they are at risk for performing sexual acts during sleep should take steps to prevent this disorder from causing harm to others. Proponents of the parasomnia defense state that behaviors can go unnoticed until the inciting event and because people with parasomnias have no conscious awareness of their actions, they cannot be held legally responsible.
Treatment and Conclusion
As with other parasomnias that have the potential for violence or significant social consequences, behavioral and environmental modifications are the mainstay of treatment. Healthy sleep hygiene, a regimented sleep-wake cycle that promotes adequate sleep, avoidance of alcohol or antagonistic medications, and treatment of disorders that fragment sleep will all minimize the likelihood of a sexsomnia event.
Medication may be required in refractory cases. Although sexsomnia has not been rigorously and independently studied, it presumably can be treated in a similar manner to other NREM parasomnias. Benzodiazepine medications, such as clonazepam, are effective treatments for RBD and NREM parasomnias.[10] Melatonin and various other medications have been studied, but little high-quality data support use of these agents.
In summary, sexsomnia is an important and often underrecognized parasomnia that can result in substantial social and legal problems. Clinicians should reflexively ask about sexual behavior during sleep if any other type of parasomnia is suspected. Interviewing bed partners is also advised. It is critical to formulate a treatment plan that centers on behavioral and environmental modification to avoid potential triggers.
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