A linkage between sleep disorder and sexual dysfunction has been studied worldwide. An underlined sleep disorder in patients suffering from erectile dysfunction could cause a failure of response to pharmacological treatment. Then, evaluation of sleep quality in these patients has to be promoted as an alternative approach to improve their outcome.

In 2002, Seftel et al. screened all the patients which reported symptoms of erectile dysfunction (ED). Using a home-made questionnaire, they found a prevalence of Obstructive Sleep Apnea Syndrome symptoms in 26.8% patients with erectile dysfunction, followed by a 13.6% of insomnia, and 2% of RLS and narcolepsy.

To our knowledge, in the last decades several studies have found a predominantly reversible association between erectile dysfunction and Obstructive Sleep Apnea Syndrome. Nevertheless, all the sexual dysfunctions could worsen with the presence of sleep disorder and many sleep disorders could lead to a reversible sexual dysfunction. An accurate assessment and management of sleep disruption can restore the normal sexual function.

Herein we report a systematic analysis of the most common sleep disturbances presenting with sexual dysfunction:

  • Severe Chronic Insomnia
  • Obstructive Sleep Apnea Syndrome
  • Narcolepsy
  • Restless Legs Syndrome

Kleine-Levine Syndrome

Kleine-Levine Syndrome is a rare disease characterized by recurrent episodes of hypersomnia and a wide range of cognitive and/or psychiatric disturbances such as compulsive behavior and mood disorders.

Kleine-Levine Syndrome is the first cause of recurrent hypersomnia usually affecting adolescent males. Patients are always tired and drowsy during the sleep attack and become irritable or aggressive when awakened or prevented from sleep. Between two different sleep episodes, patients present with attention, memory and confusion defects, derealization or hallucination, depressive mood or sometimes hypomaniac episodes, compulsive behavior and sexual disturbances. Secondary Kleine-Levine Syndrome mainly due to neurological disease involving thalamus and brain fronto-temporal areas (i.e. bilateral hypothalamic or thalamic infarct, multiple sclerosis, hydrocephalus, severe infectious or autoimmune encephalitis, brain trauma, paraneoplasia) has been reported, but a primary form of the disease is the most frequent clinical presentation. The pathophysiology of primary Kleine-Levine Syndrome is still poorly understood with possible environmental factors acting on a genetic predisposition as the most trustworthy hypothesis. Among environmental factors, Kleine-Levine Syndrome episodes could be triggered by severe encephalitis (especially viral infection), a mild to moderate head trauma, or alcohol consumption. Common pathophysiological mechanism is autoimmune encephalitis restricted to the hypothalamus and adjacent area. Indeed, an increasing permeability of blood-brain barrier facilitating the passage of circulating pathogenic agent or immunoglobulin to the brain is thought to be the most plausible pathogenic mechanism.

Sexual disorders are common in Kleine-Levine Syndrome patients. Hypersexuality is the most common symptoms presenting in more than half of the patients with a higher prevalence in men than in women. However, hyposexuality is also reported in a lower percentage of episodes (about 20%). Hypersexuality shares the same psychopathology of compulsive behavior in these patients. The intensity of these abnormal behaviors may vary. Some behaviors could be considered as mildly inappropriate when acted in a given context of education or culture (i.e. use of obscene words in front of parents or doctors). On the other hand, sexual disinhibition occurs sometimes simultaneously with other repetitive or stereotypical compulsions (i.e. setting fire), associated to a disturbed state of consciousness that is struggle to describe, and always during an attack of hypersomnia. The presence of sexual dysfunction is often associated with a worsening in the length of the disease.

Clinical examination is unremarkable in all cases of primary Kleine-Levine Syndrome. Standard EEG could sometimes detect the presence of slowed activity (delta or theta) in both fronto-temporal areas but without relevant clinical significance. Brain Magnetic Resonance Imaging is negative, but functional neuroimaging may detect a reduced cerebral blood flow in the temporal or fronto-temporal areas in some patients. Diagnosis is almost based on the clinical signs. Medical tests are aimed at eliminating other neurological causes of secondary Kleine-Levine Syndrome (mainly infections). A video-PSG could demonstrate the presence of a high length in mean Total Sleep Time during both nocturnal and 24-h recording, with an increased percentage in all sleep stages. Multiple sclerosisLT confirm the hypersomnia state with a low account of mean sleep latency and sometimes with a narcolepsy-like pattern (two or more SORapid eye movementPs).

Parasomnias and Forensic Considerations

The link between sleep and sex is very intricate. Despite the presence of sexual dysfunctions related to altered sleep-wake cycle, many patients could experience abnormal sexual behaviors during parasomnia. In the International Classification of Sleep Disorders (ICSD-2v), Parasomnia groups all sleep disorders characterized by the presence of undesirable physical phenomena that disrupt the normal sleep. The pathophysiology of this disorder is recently explained with the hypothesis of a dissociative state. According to this theory, every subject exists in one of three different states of being including awake, NRapid eye movement sleep and Rapid eye movement sleep. Each state is characterized by specific features and commonly they cycle during daytime. A dissociative state is characterized by the association of the characteristics of at least two different states of being in the same subject at the same time. Rapid eye movement Behavior Disorder and Narcolepsy are two examples of sleep disorders with a dissociative state. Many patients suffering from Rapid eye movement Behavior Disorder could report sexual content of their dream associated with a frankly sexual acts during sleep. Likewise hypnagogic or hypnopompic hallucination in narcoleptic patients could incorporate sexual content.

The so-called sexsomnia, characterized only by the recurrent presence of sexual behaviors during sleep, is the most famous parasomnia with only sleep-related sexual activities. Sleepsex behavior is rather used to define the presence of a sexualized act during a parasomnia episode. The most common sleepsex behaviors are masturbation, sexual vocalization, moaning and fondling rather than sexual intercourse itself. Sleepsex behavior could be found in patients presenting with sleep related seizures such as Nocturnal Temporal Lobe Epilepsy and in some cases of Nocturnal Frontal Lobe Epilepsy. The latter could show mainly a sexualized pelvic thrusting as hyperkinetic features of the seizures. Nocturnal Temporal Lobe Epilepsy or Nocturnal Frontal Lobe Epilepsy could also presented with sexualized acts during epileptic discharges that are sexual hyperarousal, ictal sexual automatism and ictal orgasm. Video-PSG is mandatory to detect this abnormal behavior during sleep and the typical electrophysiological features in the cases of epilepsy.

Sleep-related painful erection is another form of parasomnia defined by the ICSD-2v as penile pain that occurs during Rapid eye movement-sleep related erection. This condition could determine frequent awakenings of the subject finally leading to a reduced sleep quality with a compliant of excessive daytime sleepiness. The erection and pain completely ceased as soon as patients awoke, while erections in the awaking state did not produce pain. Sometimes patients could present some genital abnormalities (such as Peyronie’s syndrome) or neurological injuries (such as compression of the anterior hypothalamus), but in most cases there is no evidence of urologic or neurologic disease. Some patients may experience an increasing libido or sexual activity in the effort to reduce or avoid the painful erection. Video-PSG shows reduced sleep efficiency with frequent awakenings during Rapid eye movement-sleep related erection.

Furthermore, some sexualized parasomnias are recognized in patients with brain injury or as clinical feature of psychiatric diseases. Hypersexuality in the transition from sleeping to waking is the most common sexual dysfunction in these patients. Moreover, sleep could exacerbate a condition of persistent sexual arousal syndrome, whereas the genital sensation and urges of achieving orgasm is not accompanied by any subjective sexual desire.

The linkage between parasomnia and sexuality is recently growing in importance for forensic implication in sexual abuse crime, especially in minor. Some legal defense in different crimes (especially homicide) are built upon the absence of full alertness or impairment of brain function related to sleep disorder. In the last years a large number of defendant’s lawyers adopted the so-called “sleepwalking defense”. This kind of defense is based on the scientific evidence of some NRapid eye movement parasomnia predisposing, priming and precipitating factors in adults, especially in the subjects having a familiar and personal history of parasomnia. In the last years, this defensive line has been critically reviewed for the following two main considerations. Firstly, “the knowledge of a parasomnia with a low frequency of presentation in childhood is a physiological feature, becoming a disease only if it remains in adult age”. Secondly “the set of circumstances resulting in a sexual misconduct during presumed parasomnia have to be extraordinary, unique and not ever more repeatable”. Then, continuous sexual abuses made by a person aware of his parasomnia are legally culpable.

In 2002, Guilleminault et al. advised a flow-chart for the management of patients reported an abnormal sexual behavior during sleep or sleepsex. First of all, an extensive history of the patients should be performed including a detailed description of the event, exhaustive family and personal history with particular attention to sleep disorders such as parasomnia, habits like drug use or alcohol intake and psychiatric evaluation. Moreover, the history should be accompanied with interviews of bed partner or family members to highlight the description, frequency, nature (i.e. age of onset, stereotypical or not) of the event, attitude of the subject when awake or after a sleep-related event. A comprehensive neurological workout, including EEG studies and video-PSG is useful to confirm the diagnosis and to avoid possible complex partial seizures potentially responsible for the behavior.

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