For most of my life I have “suffered” from insomnia. I deliberately put the word ‘suffered’ in quotation marks as for the vast majority of the time I have always seen my lack of sleep as something positive (i.e., I had more time to do other things. In fact, when people ask me how I find the time to write so much, I usually say “Insomnia” but I don’t usually say it as a joke, it’s a matter of fact). Given my personal interest in insomnia, I’ve always enjoyed reading papers on insomnia (and no, they don’t send me to sleep!) and sexsomnia (which I looked at in a previous blog). In 1990, a Finnish man named Toimi Soini stayed awake for over 11 days (276 hours) and broke the world record for not going to sleep. However, this record no longer appears in the Guinness Book of World Records as it was withdrawn on health grounds because lack of sleep – as I’ll show in today’s blog – can lead to death.
One of the strangest (and deadliest) types of insomnia is ‘fatal familial insomnia’ (FFI). This is actually an incredibly rare genetic sleep disorder that affects around 40 families worldwide. The cause of FFI is a genetic mutation that leads to prion disease and is therefore related to bovine spongiform encephalopathy (BSE; i.e., ‘mad cow disease’), Creutzfeldt–Jakob disease (the human form of BSE), and ‘Kuru’ (the incurable and degenerative neurological disorder found in the cannibalistic tribes in New Guinea and known as the ‘laughing disease’). The (online) Medical Dictionary is a little more technical and notes:
“Fatal familial insomnia (FFI) is a very rare, autosomal dominant inherited, disease of the brain. It is caused by a mutation in a protein called prion protein (PrP): asparagine- 178 is replaced by aspartic acid. The mutation changes the shape of PrP so that it becomes a prion and makes other, normal PrP molecules change to the abnormal shape. This causes amyloid plaques in the thalamus, the region of the brain responsible for regulation of sleep patterns. The dysfunction of the thalamus results in insomnia first of all, which progresses to more serious problems over several years”
All prion diseases (known more scientifically as ‘transmissible spongiform encephalopathies’) are rare progressive neurodegenerative disorders that can affect both animals and humans. All of the prion diseases (including FFI) typically have (i) long incubation periods, (ii) a failure to induce inflammatory response, and (iii) characteristic spongiform changes that are associated with neuronal loss. The first recorded case of FFI is thought to be an Italian man who died in Venice in 1765. There are many descriptions of the disease online including case study accounts. The Wikipedia entry on FFI described the case of the American music teacher, Michael Corke from Chicago:
“He suddenly began to have trouble sleeping not long after his 40th birthday in 1991, and his health and state of mind quickly deteriorated as his sleeplessness grew worse. Eventually, he couldn’t sleep at all, and he was soon admitted to the hospital. Doctors there weren’t sure what was wrong with him, initially diagnosing multiple sclerosis; in a bid to send him to sleep in the later stages of the disease, physicians induced a coma with the use of sedatives, but they found that his brain still failed to shut down. Corke died in 1992 a month before his 41st birthday, by which time he had gone without sleep for six months”
Another 2011 online article on “bizarre brain disorders” by Anna McGann also described a family case study (which is very similar to paper published in a 2000 issue of the Journal of Neurology, Neurosurgery and Psychiatry by Dr. C. Tabernero and colleagues):
“Dr. Ignazio Rottier gained unwanted firsthand experience when he and his wife, Elisabetta, watched her family fall victim to [FFI]. First known to fall ill was Elisabetta’s grandfather. Decades later, Elisabetta’s uncle, Silviano, was 53 when he lost his ability to sleep. A few short months following initial onset, Silviano fell into a coma and died…In the 70s, an aunt of Elisabetta’s passed on, one year after her own initial onset of sleeplessness. Yet another year later, a second aunt too lost her life battling the very same affliction”.
Research has also shown that the condition (in a few cases) can result from a non-inherited genetic mutation that has been called ‘sporadic fatal insomnia’ (sFI). Less than 10 cases of sFI have ever been documented in the medical literature. As the conditions worsen, sufferers experience a wide range of symptoms including delirium, hallucinations (auditory, visual and tactile), elevated heart rate and blood pressure, hyperhidrosis (i.e., excess sweating), hyperthermia, hypertension, impotence (in men), amenorrhea (cessation of periods) and early menopause (in women), constipation, and dementia. Treating the symptoms (via vitamin therapy, meditation, use of narcoleptics) may extend the quality of life (but as noted above, there is no known cure and most interventions are purely palliative). The disease typically has four stages, and takes between half a year and a year and a half to run its course:
- Stage 1 (typically four months): Symptoms include insomnia, paranoia, phobias and panic attacks.
- Stage 2 (typically five months): Symptoms include severe hallucinations and increasing panic attacks.
- Stage 3 (typically three months): Symptoms include permanent insomnia, limited mental functioning, and rapid weight loss.
- Stage 4 (typically six months): Symptoms include dementia and general non-responsiveness leading to death.
Writing in a 2006 issue of the Medscape General Medicine journal, Dr. Joyce Schenkein outlined the etiology and characteristics of FFI. She noted that it often begins in middle age (average age of onset being 50 years) and has no cure (even ‘gene therapy has been unsuccessful to date). Unfortunately, the prognosis following initial diagnosis is poor with FFI sufferers’ only living for an average of about a year and a half (with Dr. Schenkein noting that survival ranged from 7 to 36 months from diagnosis of FFI). It originates in the form of unexplained sleeplessness before rapidly developing into a fatal insomnia. Writing in an issue of the Journal of Clinical Neuroscience, Dr. S. Collins and colleagues in a paper on prion diseases (including FFI) concluded:
“FFI [is] likely [to] remain, [a] very rare disease, [and] will be increasingly recognised as heightened clinical awareness prompts appropriate confirmatory genetic and other testing. Similarly, continued molecular biological and allied research of these less common prion diseases will undoubtedly provide fundamental insights into the pathogenesis of this group of disorders in general, disproportionate to their numerical frequency”.
Dr Mark Griffiths, Professor of Gambling Studies, International Gaming Research Unit, Nottingham Trent University, Nottingham, UK
Collins, S., McLean, C.A. & Masters, C.L. (2001). Gerstmann–Sträussler–Scheinker syndrome, fatal familial insomnia, and kuru: a review of these less common human transmissible spongiform encephalopathies. Journal of Clinical Neuroscience, 8, 387–397.
McGann, A. (2011). 5 bizarre brain disorders. Suite 101, November 25. Located at: http://suite101.com/article/5-bizarre-brain-disorders-a397906
Moody, K.M., Schonberger, L.B., Maddox, R.A., Zou, W.Q., Cracco, L., & Cali, I. (2011). Sporadic fatal insomnia in a young woman: a diagnostic challenge: case report. BMC Neurology, 11, 136.
Schenkein, J. (2006). Self-management of fatal familial insomnia. Part 1: What Is FFI? Medscape General Medicine, 8(3), 65.
Schenkein, J. & Montagna, P (2006). Self-management of fatal familial insomnia. Part 2: Case report. Medscape General Medicine, 8(3), 66.
Tabernero, C., Polo, J.M., Sevillano, M.D., Muñoz, R., Berciano, J., Cabello, A., Báez, B., Ricoy, J.R., Carpizo, R., Figols, J., Cuadrado, N., Claveria, L.E. (2000). Fatal familial insomnia: clinical, neuropathological, and genetic description of a Spanish family. Journal of Neurology, Neurosurgery and Psychiatry, 68, 774–777.
Turner, R. (2012). Fatal Familial Insomnia: The FFI Sleep Disorder. World of Lucid Dreaming. Located at: http://www.world-of-lucid-dreaming.com/fatal-familial-insomnia.html
Wikipedia (2012). Fatal familial insomnia. Located at: http://en.wikipedia.org/wiki/Fatal_familial_insomnia
Somnophilia is a sexual paraphilia in which sexual arousal is derived from intruding on, caressing, and/or fondling someone (typically a stranger) while they are asleep without force or violence. However, some definitions of somnophilia – while all connected with sleep – sometimes slightly differ. For instance, some definitions of somnophilia say that it refers to actually having sexual intercourse with a sleeping partner (rather than just touching someone sexually while they are asleep). Another definition I came across says that somnophilia also includes having sex with someone while they are unconscious. This latter variation may have come about by the increased use of drugs such as rohypnol (“roofies”) that have been implicated in sexual offences such as ‘date rape’. There is no technical term for the reciprocal condition of being the recipient of sexual advances while asleep. This is thought to occur more often in fantasy than in reality.
Some signs or symptoms that may point to somnophilia include recurring thoughts regarding unconscious or sleeping individuals and feeling sexual urges when in contact with or in the proximity of those people. While there is speculation about treatment (e.g., hypnosis, behavioural therapy and 12-step programs), it is not needed unless the behavior becomes destructive, problematic, and/or involves sexually criminal activity and becomes a legal issue.
Empirically, very little is known about somnophilia and as far as I am aware there are no data concerning its prevalence, etiology, or treatment (not even a single case study). Various sexologists and authors have made reference to it (such as John Money, Nancy Butcher and Rudy Flora). The historian Richard Burg (Arizona State University) published a 1982 article in the Journal of the History of the Behavioral Sciences, and suggested the possibility of a continuum of erotic focus from somnophilia fantasy through to acts involving necrophilia. In fact, sometimes somnophilia has been described as ‘pseudo-necrophilia’ in that both paraphilias involve having sex with a human that is not aware and/or conscious, and have not given consent.
In a 1972 issue of the International Journal of Psychoanalysis, the psychologists Dr. Victor Calef and Dr. Edward Weinshel decribed somnophila as ‘Sleeping Beauty Syndrome’ and asserted that somnophilia was the neurotic equivalent of necrophilia. As they asserted:
“The theme of the ‘Sleeping Beauty’ who is brought back to life, as it were, by the love of a Prince Charming is one which has fascinated both story-tellers and listeners for hundreds of years. It is our impression that not infrequently we hear, from our analytic patients —primarily via various denials — this same theme and its disguised wishes. We are referring to those patients who complain that their spouses go to sleep before them and before sexual activity can be initiated. It is our experience that, at least in many of these individuals, this complaint is an attempt to hide the fascination and attraction for the sleeping sexual object and the wish to make love to that object”.
However, they ultimately concluded that although somnophilia appears to have some characteristics in common with necrophilia, the two syndromes do not necessarily reflect the same underlying pathology. Using Freudian theory, Calef and Weinshel speculated that underlying somnophilia was the desire to return to the maternal womb, and that somnophiliacs had unresolved Oedipal complex issues, fixations on pre-genital stages of psychosexual development, and castration anxiety. However, as with almost all psychoanalytic theory, it is hard to design any research to either confirm or deny such speculations.
In researching the topic of somnaphilia, I did come across a 2006 paper by Mark Knowles (New School for Social Research, New York) that examined the sexual content of the letters written by Irish novelist James Joyce (1882-1941). The primary purpose of Knowles’ paper was to examine the ways in which the paraphilic sexual fantasies of Joyce were expressed in his relationship with his wife (Nora Barnacle) via letters written at the end of 1909. Most of the paraphilic writings concerned coprophilia (sexual interest in faeces), but in one letter (dated December 8), Knowles noted there was also an instance of somnophilic fantasy. Here, Joyce writes of how he will perform cunnilingus on his wife in an effort to “surprise [her] asleep.” This will cause her to “groan and grunt and sigh and fart with lust in [her] sleep”.
Knowles claimed that investigators have suggested that the etiology of somnophilia is similar to that of fetishism and coprophilia (although these “investigators” were not referenced – although he did cite the paper by Calef and Weinshel). Knowles noted:
“The degree to which Joyce’s own aberrant libidinal impulses were influenced by factors such as these is uncertain; however, the fact that castration anxiety has been posited as a causal mechanism with regard to somnophilia as well as fetishism and coprophilia, the latter two of which played salient roles in his sexual fantasies, lends credence to the notion that the threat of castration did indeed constitute Joyce’s ‘nuclear complex’”.
Christina Eugene (Bowling Green State University, USA) also made some interesting observations in her 2006 thesis ‘Potent Sleep: The Cultural Politics of Sleep’. She asserted:
“Sleep is the essential objectifier of all life. The passivity of sleep transforms subjects into inanimate objects, and in doing so removes the subject’s privilege of being able to act on the world of objects… This rendering of people into inanimate objects allows them to be fundamentally treated as objects – consumed, fetishized, and controlled. In accordance with the totality of capitalism and phallocentrism, an erotic fetish for sleeping beauties has surfaced”.
Eugene also makes heavy reference to Carolyn Fay’s 2002 (University of Virginia, USA) thesis ’Stories of the Sleeping Body: Literary, Scientific and Philosophical Narratives of Sleep in Nineteenth Century France’. Although not actually using the word ‘somnophilia’, Fay says that:
“Contemporary sleep fetish culture is driven by the idea that the sleeping person is an absent person…To the fetishist, sleep is that perfect moment when consciousness is evacuated, leaving a living, breathing fragment, worthy of love”. [Men who seek to actualize their desire to have intercourse with a sleeping woman may use drugs to maintain the unconscious state] “for if the person wakes up, the fantasy and the fetish object become lost”
In response to this, Eugene thus claims that somnophilia emphasizes:
“The conflating of absence and passivity because rather than her being passive, the fetish is maintained by her absence. What are the dynamics that created these perplexities? What can account for both the sleeping beauty fetish and the somnaphobia of a culture where people are disposed to self-inflicting the torture of sleep deprivation? Despite the sheer obscurity of this fetish culture, both are, nevertheless, an exemplification of particular cultural messages that are written onto the sleeping body”.
Given that I prefer empirical data, I’m not sure whether these debates in the Arts and Humanities literature add to what we know scientifically know about somnophilia, but at the very least they make an interesting read about the human condition. In the absence of anything in the empirical literature, I did spend ages trying to find some kind of case study and this was the best I could come up with:
“I have a fetish that I have found out is called somnophilia. I have told this to my girlfriend and she has no problem with it, or with allowing me to fulfill my fantasy with her, since she is very submissive. The only problem is, she’s an extremely light sleeper. As in, she wakes up at the drop of a hat. For this reason, there’s really no way for me to do it naturally. I have tried artificial methods such as [over-the-counter] sleeping pills. However, these just make her drowsy, but don’t affect her depth of sleep (i.e., she still wakes up right away). I am looking for either a method or a drug that will put her into a very deep sleep, or even leave her unconscious, such as you would be under the influence of a general anesthetic during surgery. I guess I would need a very powerful sedative/hypnotic. I have heard of drugs such as Rohypnol, but I know that these are illegal in the US, and I’m not trying to get into any trouble here. I considered asking a pharmacist, but I’m worried they’d think I’m looking for a ‘date rape drug’ for illegal purposes and call the cops on me. I’m looking for something that’ll knock her out and will withstand a vigorous activity like sex”.
Although there is little detail here, and there is no way of checking the veracity, this plea does at least suggest that somnophilia is more than a theoretical paraphilia.
Dr Mark Griffiths, Professor of Gambling Studies, International Gaming Research Unit, Nottingham Trent University, Nottingham, UK
Burg, B.R. (1982). The sick and the dead: The development of psychological theory on necrophilia from Krafft-Ebing to the present. Journal of the History of the Behavioral Sciences, 18, 242-254.
Butcher, N. (2003). The Strange Case of the Walking Corpse: A Chronicle of Medical Mysteries, Curious Remedies, and Bizarre but True Healing Folklore. New York: Avery.
Calef, V., & Weinshel, E. M. (1972). On certain neurotic equivalents of necrophilia. International Journal of Psychoanalysis, 53, 67-75.
Eugene, N.C. (2006). Potent Sleep: The Cultural Politics of Sleep. Master’s Thesis, Bowling Green State University, American Culture Studies/English.
Fay, C.M. (2002). Stories of the Sleeping Body: Literary, Scientific and Philosophical Narratives of Sleep in Nineteenth Century France. Diss. U Virginia, 2002. Ann Arbor: UMI.
Flora, R. (2001). How to Work with Sex Offenders: A Handbook for Criminal Justice, Human Service, and Mental Health Professionals. New York: Haworth Clinical Practice Press.
Joyce, J. (1975). Selected letters of James Joyce. R. Ellmann (Ed.), New York: Viking Press.
Knowles, J.M. (2006). Nora’s Filthy Words: Scatology in the Letters of James Joyce. The New School Psychology Bulletin, 4, 91-101.
Love, B. (1992). Encyclopedia of Unusual Sex Practices. Fort Lee, NJ: Barricade Books
Money, J. (1986). Lovemaps: Clinical concepts of sexual/erotic health and pathology, paraphilia, and gender transposition in childhood, adolescence, and maturity. New York: Irvington.
Over the last decade there have been an increasing number of papers published on sexsomnia (more commonly known as ‘sleep sex’). There have also been a lot of high profile media cases where women have claimed that their sexsomnia has ruined their lives or men who have been arrested for committing sexual assaults while asleep. Sexsomnia is a condition that is highly prevalent among sleepwalkers and is where people engage in sexual acts while still asleep and can include masturbating and fondling of either themselves or others, or oral sex and sexual intercourse with another person.
Sexsomniacs do not recall or remember anything that they did while asleep which raises interesting questions if criminal sexual acts are performed without the person being aware that they have even done anything wrong. Some in the field have claimed the disorder is relatively common but often goes unreported because of shame and embarrassment related to the condition. In addition to sleepwalking, other sleep-related disorders that sexsomniacs may suffer from include nightmares, bedwetting, and sleep apnea (abnormal breathing while asleep). Many of these behaviours are known as parasomnias (i.e., sleep disorders that involve abnormal and unnatural movements, behaviors, emotions, perceptions, and dreams and are events that occur intermittently or episodically during the night).
The first academic paper on sex during sleep was published in the mid-1990s in the journal Sleep Research by Canadian researchers Colin Shapiro, Nik Trajanovic and Paul Federoff (at the Universities of Toronto and Ottawa). They claimed that having sex during sleep could be conceptualized as a new type of parasomnia. Then, in 1998, the term ‘sleepsex’ was first used in a paper published in the Archives of Sexual Behavior by American neurologists Dr. David Rosenfeld and Dr A.J. Elhajjar. They described two case studies of people having sex while asleep. The more interesting second case concerned a sleepwalker who committed a sexual assault and used somnambulism as his legal defence. In 2003, the term ‘sexsomnia’ was first used by Shapiro, Trajanovic and Federoff in a case report published in the Canadian Journal of Psychiatry.
Unsurprisingly, sexsomniacs are often told by others that they are engaging in sex while asleep, and for many the disorder may not be problematic – particularly within the confines of a stable romantic relationship. According to a 2007 paper by Dr Michael Mangan (University of New Hampshire, USA) and Dr. Ulf Reips (Zurich University, Switzerland), some couples embrace sexsomnia, describing it as an exciting addition to their normal waking sex lives. The behaviour may have been going on a long time – sometimes years – before they seek medical help. Despite many people not believing that sexsomnia is a genuine medical condition, the condition has been confirmed by various sleep disorder specialists by video recording sufferers while they are asleep.
In 2007, Dr Carlos Schenck and co-workers (University of Minnesota Medical School, USA) reported in the journal Sleep, that bouts of sexsomnia can be triggered by such factors as physical contact with another person in bed (64%), stress (52%), fatigue (41%), alcohol use (14.6%), and drug abuse (4.3%). Sleep deprivation was also identified as a risk factor.
In 2003, Shapiro and his Canadian colleagues asserted that sexsomnia should be considered a distinct entity in the family of parasomnias, since there was were specific motor, and autonomic activation systems. However, they did make the point that it can be difficult to distinguish between typical sleepwalking and sexsomnia. They claimed that the uniqueness of the condition is the involvement of a partner (usually more than a witness). A recent 2011 review published in the Delhi Psychiatry Review pointed out the main differences between sleepwalking and sexsomnia:
- Sexsomnia originates in most cases from non-rapid eye movement sleep (whereas sleepwalking usually originates from slow wave sleep)
- Sexsomina can occur any time during sleep (whereas sleepwalking usually occurs in the first one-third of the night)
- Sexsomnia involves widespread autonomic activation (whereas in sleepwalking autonomic activation is largely limited to cardio-respiratory functions
- Sexsomnia involves frequent sexual arousal frequently (whereas in sleepwalking sexual arousal is not present)
- Sexsomnia bouts possibly exceed 30 minutes (whereas sleepwalking bouts are usually under 30 minutes)
- Sexsomnia can involve exceptional violence or injurious behaviour (whereas sleepwalking involves occasional violence, injury, and self-injury)
- Sexsomnia occurs predominantly in adults (whereas sleepwalking predominantly occurs in children)
These bullet point differences do at lest suggest that sexsomnia and sleepwalking may be distinct clinical entities. Shapiro and colleagues state that the main features of sexsomnia often include sexual arousal with autonomic activation (including nocturnal erection, vaginal lubrication, nocturnal emission, wet dreams, sweating, and cardio-respiratory response). However, there are some case studies reported in the literature that do not appear to have shown signs of sexual arousal. Despite these differences, most sleep experts consider sexsomnia to be a variant of sleepwalking, as most sexsomniacs also sleepwalk.
Based on a review of all the published case studies, Dr Andersen and her colleagues asserted that sleep sex somnambulism was a predominantly male disorder, but that the basis for male predominance in sexsomnia is not known. They further reported that females almost exclusively engaged in masturbation and sexual vocalizations, whereas males commonly engaged in sexual fondling and sexual intercourse with females.
Mangan and Reips carried out an online survey using visitors to the Sleepsex.org website (run by Dr. Mangan). Data were collected over a three-month period and generated 226 responses. Up until their 2007 study, only seven academic papers had been published with the number of sexsomniacs totaling 30 cases (the largest sample size being 11 people and six of these were reported in a previous paper by the same authors). Unfortunately, the focus of the paper was on how the internet can be used to collect data on little studied groups and as such presented very few of the results. They noted that adult sexsomniacs sometimes coming into contact with minors (in this survey 6%), and that the legal implications of reporting this are serious.
Using the same dataset, Nik Trajanovic, Michael Mangan and Colin Shapiro joined forces and published yet another paper from the Sleepsex.org data in the journal Social Psychiatry and Psychiatric Epidemiology. The results showed that females accounted for almost one-third of the sample (31%) and that the mean age of the total sample was just over 30 years of age. The participants typically reported multiple sexsomnia episodes that were typically ptriggered by body contact, stress and fatigue. A small number of participants reported that their sexsomniac behaviour had led to police and legal intervention (8.6% males and 3% females) some of which had involved minors (6% of the total sample). The authors claimed the study confirmed previous anecdotal evidence about the gender and age distribution, trigger factors, and medico-legal aspects.
An earlier 2004 paper by Dr Mangan published in the Archives of Sexual Behavior, examined first-person reports of individuals’ experiences of sexsomnia. Qualitative analysis of 121 sexsomniacs resulted in six distinct themes: (i) fear and a lack of emotional intimacy; (ii) guilt and confusion; (iii) a sense of repulsion and feelings of sexual abandonment; (iv) shame, disappointment, and frustration; (v) annoyance and suspicion; (vi) embarrassment and a sense of self-incrimination. Mangan claimed that his results suggested that sexsomnia can elicit negative emotions and cognitions that may become a source of personal and relational distress.
Research published in 2010 by Lisa Klein and Dr. Daniel Houlihan (both at the Minnesota State University, USA) in the International Journal of Sexual Health examined relationship and sexual satisfaction, sexual functioning, and sexual desire in 32 sexsomniacs who were recruited online. Compared to controls, sexsomniacs reported lower levels of sexual satisfaction, lower levels of relationship satisfaction, and similar levels of sexual desire. They also reported that more frequent incidence of sexsomnia resulted in lower sexual satisfaction. However, frequency was not found to impact on the level of sexual desire or relationship satisfaction Four-fifths of the sexsomniacs (81%) also reported at least one sexual problem.
A review paper led by Dr Monica Andersen (Universidade Federal de São Paulo, Brazil) published in a 2007 issue of Brain Research Reviews, attempted to assemble the characteristics of sexsomniacs based on the small empirical base. They noted the sexsomnia should receive more attention and concluded:
“Reports describing sexual activity of sleeping humans are still rather infrequent and the etiology of this peculiar sleep disorder is still obscure… Moreover, sexsomnia is often a longstanding disorder that carries major adverse physical, psychosocial, and legal consequences. We anticipate that this condition is currently underreported”.
Andersen, M.L., Poyares, D, Alves, R.S.C., Skomro, R. & Tufik, S. (2007). Sexsomnia: Abnormal sexual behavior during sleep. Brain Research Reviews, 56, 271-282
Anubhav, R. & Bhatia, M.S. (2011). Is Sexsomnia a New Parasomnia? Delhi Psychiatry Journal, 14, 378-380.
Klein, L.A. & Houlihan, D. (2010). Relationship satisfaction, sexual satisfaction, and sexual problems in sexsomnia. International Journal of Sexual Health, 22, 84-90.
Mangan, M. A. (2004). A phenomenology of problematic sexual behavior occurring in sleep. Archives of Sexual Behavior, 33, 287-293.
Mangan, M. A. & Reips, U. (2007). Sleep, sex, and the Web: Surveying the difficult-to-reach clinical population suffering from sexsomnia. Behavior Research Methods, 39, 233-236.
Rosenfeld, D.S. & Elhajjar, A.J. (1998). Sleepsex: A variant of sleepwalking. Archives of Sexual Behavior, 27, 269-278.
Schenck, C.H., Mahowald, M.W. (2005). Rapid eye movement and non-REM sleep parasomnias. Primary Psychiatry, 12(8), 67-74.
Schenck, C.H., Arnulf, I., Mahowald, M.W., 2007. Sleep and sex: what can go wrong? A review of the literature on sleep related disorders and abnormal sexual behaviors and experiences. Sleep, 30, 683–702.
Shapiro, C.M., Fedoroff, J.P., & Trajanovic, N.N. (1996). Sexual behavior in sleep: A newly described parasomnia. Sleep Research, 25, 367.
Shapiro, C.M., Trajanovic, N.N., & Fedoroff, J.P. (2003) Sexsomnia: A new parasomnia? Canadian Journal of Psychiatry, 48, 311-317.
Trajanovic, N.N., Mangan, M. & Shapiro, C.M. (2007). Sexual behaviour in sleep: An internet survey. Social Psychiatry and Psychiatric Epidemiology, 42, 1024-1031.