ReviewSexsomnia: Abnormal sexual behavior during sleep☆
Introduction
The fact that sleep is promptly reversible is probably the most important characteristic which differentiates it from most other states of altered consciousness. Electrophysiological studies in the 1950s demonstrated that there were two main states of sleep, non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. The NREM sleep is recognized by low-frequency and high-amplitude waves, presence of sleep spindles on an electroencephalogram (EEG) recording, and muscle tone reduction. The electrophysiological features of REM sleep are a combination of desynchronized EEG, loss of electromyogram (EMG) activity, and the presence of rapid eye movements. The EEG reflects the intense cortical activity that distinguishes REM from NREM sleep, but its similarity to the EEG of wakefulness also led it to be called “paradoxical” sleep.
The homeostatic sleep drive appears to control NREM rather than REM sleep. Sleep is normally entered through NREM rather than REM sleep in adults with intensification of the homeostatic drive increasing the duration and depth of NREM sleep at the expense of REM. NREM sleep provides time for restorative processes to take place within the central nervous system (CNS) and other parts of the body. Overall, NREM sleep appears to be a state in which energy is conserved enabling both the CNS and other systems to either recover from the activity of the previous episode of wakefulness or to prepare for the next episode. In this sense, NREM, REM sleep, and wakefulness are not mutually exclusive states. The occurrence of states of incomplete awakening from sleep may generate parasomnias (Wills and Garcia, 2002).
Section snippets
Parasomnias
Sleep is a vital behavior and occupies approximately one-third of a person's lifetime. The incidence of both sleep fragmenting disorders and chronic partial sleep deprivation is very high in our society (Bonnet and Arand, 2003), leading to a dramatic surge in the occurrence of sleep complaints and somnolence. There are several types of sleep disorders, one of the most fascinating of which is a category of parasomnias: well described and common nocturnal phenomena defined as “events that occur
Sexsomnia: atypical sexual behavior during sleep
One of the most intriguing clinical entities of parasomnia is a distinct variant of sleepwalking known as sexsomnia, somnambulistic sexual behavior or “sleepsex” (Buchanan, 1991, Fenwick, 1996, Shapiro et al., 1996, Shapiro et al., 2003). Recently, Schenck et al. (2007) advocated the use of the terms pertaining to abnormal sleep and sex as sleep-related abnormal sexual behaviors, sexual behavior in sleep, among others. The authors went on to formulate the first classification of sleep-related
Background
Even though there is scant literature on this subject, there is at least one early report of sexual behavior during sleepwalking. In the Annales d'Hygiene et de Médecine Légale in 1897, Motet described a case of somnambulism and exhibitionism (see Thoinot, 1911). E.D. was arrested outside a public urinal on Rue Saint-Célie, where he had remained for more than half an hour attempting to entice a policeman by exposing his genitals. When he emerged from his state of half stupor, he claimed to
Physiological genital events during sleep
In 1944, Ohlmeyer and co-workers discovered the occurrence of penile erection cycles during sleep in adult males. Such sleep-related erections (SRE) appeared at 85-min intervals and had an average duration of 25 min (Ohlmeyer et al., 1944). As a result of this initial study, Oswald (1962) noted that erection accompanied some REM periods, but subsequent investigations of Fisher et al. (1965) and Karacan et al. (1966) demonstrated a strong temporal association between the occurrence of erection
Precipitants of parasomnic behavior
Different trigger factors can precipitate a sleep automatism and should be identified when sexsomnia event occurs. The most common precipitants of a recurrence of parasomnic behavior in adults are stress, sleep deprivation/fragmentation, alcohol or drug consumption, excessive fatigue (tiredness), and physical overactivity in the evening. As pointed out by Schenck and co-workers (2007) precipitating factors for sexsomnia included physical contact with another person in bed (64%), stress (52%),
Medico-legal issues
It is not unusual that after an all-night party single people sleep over at a friend's house, but, it has now become socially acceptable, in some cultures, for men and women to sleep together in the same room and even in the same bed, even if they have not known each other well (Fenwick, 1996). Thus, it is not surprising that an increasing number of criminal cases are coming before the courts where the interaction of sexual behavior and sleep is reported to have led to an offence, usually rape
Diagnostic aspects
The history must include detailed description of the event and the degree of amnesia, current, past medical, as well as family history. Moreover, it should elicit presence of previously mentioned potential risk factors such as alcohol, drug or medication intake, sleep deprivation, stressful life event, anxiety, etc. prior to parasomnic episode. It is also recommended that social habits, employment records, and determination of the frequency of violence and its stereotypic nature are
Treatment
Safety precautions and good general sleep hygiene measures are recommended for individuals with a parasomnia (Wills and Garcia, 2002). When associated syndromes are recognized, their specific treatment is also a priority. Of note, patients with parasomnias, sleep apnea, and restless legs syndrome should be questioned (with their bed partners) about any associated sleepsex, as pointed by Schenck and co-workers (2007). Most primary motor parasomnia cases reported in the literature show a positive
Final considerations
In the last few decades, we have experienced a remarkable increase in knowledge about human behavior during sleep, and about how sleep disorders (e.g. parasomnias) can emerge or be induced. We have also improved our diagnostic skills and treatment options of these disorders. Reports describing sexual activity of sleeping humans are still rather infrequent and the etiology of this peculiar sleep disorder is still obscure. It is not clear if this constitutes a new clinical entity of parasomnias,
Acknowledgments
The authors would like to express their cordial thanks to Tathiana A.F. Alvarenga for kind assistance. This work was supported by grants from Associação Fundo de Incentivo à Psicofarmacologia (AFIP) and Fundação de Amparo à Pesquisa do Estado de São Paulo (CEPID #98/14303-3 to ST).
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THEME: Neural Basis of Behavior: Biological rhythms and sleep/Brain Research Reviews