Painful nocturnal erection

Sleep related painful erection is a parasomnia occurring during rapid eye movement (REM) sleep. It is rarely dealt with in the literature, and is very often poorly understood. Because of repeated awakenings, it is interpreted as insomnia, and is attributed to anxiety. EEG recordings associated with nocturnal penile tumescence monitoring indicate the existence of disturbed sleep organization, with awakenings during REM sleep and frequent nocturnal erections, often unrelated to REM sleep. Though the pathophysiological mechanisms involved are not yet understood, an interpretation of sleep-related painful erections is proposed, based on the current understanding and physiology of diurnal and nocturnal erections.     

Forerunners of REM sleep

The development of sleep research can be divided into two main periods. The first one was initiated in 1863 by the first systematic measurement of the depth of sleep, the second in 1953 by the discovery of recurrent episodes of rapid eye movements in sleep. The main methodological procedure in the first of these two periods was the measurement of a single physiological variable, while beginning with long-term measurements of the electroencephalogram (EEG) in sleep, multi-channel, polygraphic recording became the method of choice for sleep studies. Although rhythmic changes in the ultradian frequency range of one to 2?h were observed early in many variables during sleep (movements, autonomic functions, penile erections), the recognition of the existence of two different states of sleep (rapid eye movement (REM) and non-rapid eye movement (NREM sleep)) was contingent upon a 'synthetic' view, which focus on the coalescence of multiple variables. The dual concept of sleep organization evolved stepwise in parallel to the rapid growth of neurophysiological knowledge and techniques in the first half of the 20th century, culminating in the discovery of REM sleep.     

Sleep-related erections: Neural mechanisms and clinical significance

Penile erections during rapid eye movement (REM) sleep are a robust physiologic phenomenon in all normal healthy males, irrespective of age. Given the involuntary nature of erections in sleep, sleep-related erection (SRE) testing has been used to differentiate psychogenic from organic impotence. The historical background of nocturnal penile tumescence, its current use, and common misconceptions of SRE testing are discussed. An animal model has been developed to study SRE mechanisms and has provided a new neural model regarding REM-related erectile control. The implications of these recent data on clinical SRE evaluation are presented. Finally, guidelines regarding SRE testing with polysomnography have not been available, contributing to a decline in formal SRE testing even though erections in sleep are commonly evaluated by urologists using home screening devices that do not record sleep. We propose a set of clinical indications when formal SRE evaluation in a sleep laboratory should be considered.     

Seizures in a Fetal Lamb After Cocaine Exposure: A Case Report

We report the chance observation of two generalized seizures in a fetal lamb that received cocaine. Cocaine was infused intravenously into a 138-day-old fetus while electrocortical (ECoG), electroocular (EOG), and neck electromyographic (EMG) activity were recorded. Fetal rapid eye movement (REM) and nonrapid eye movement (NREM) sleep were disrupted during the cocaine exposure and returned to a normal pattern after infusions were stopped. Seventy-two hours later, however, we recorded generalized seizures with ECoG spike and spike wave activity.     

Role of the lateral preoptic area in sleep-related erectile mechanisms and sleep generation in the rat.

Penile erections are a characteristic phenomenon of paradoxical sleep (PS), or rapid eye movement sleep. Although the neural mechanisms of PS-related erections are unknown, the forebrain likely plays a critical role (Schmidt et al., 1999). The preoptic area is implicated in both sleep generation and copulatory mechanisms, suggesting it may be a primary candidate in PS erectile control. Continuous recordings of penile erections, body temperature, and sleep-wake states were performed before and up to 3 weeks after ibotenic acid lesions of the preoptic forebrain in three groups of rats. Neurotoxic lesions involving the medial preoptic area (MPOA) and anterior hypothalamus (n = 5) had no significant effects on either erectile activity or sleep-wake architecture. In contrast, bilateral lesions of the lateral preoptic region, with (n = 4) or without (n = 5) MPOA involvement, resulted in a significant decrease in the number of erections per hour of PS, number of PS-related erections, and PS phases exhibiting an erection. Lesion analysis revealed that the candidate structures for PS erectile control include both the lateral preoptic area (LPOA) and ventral division of the bed nucleus of the stria terminalis; however, lesions of the LPOA were the most effective in disrupting PS erectile activity. LPOA lesioning also resulted in a long-lasting insomnia, characterized by the significant increase in wakefulness and decrease in slow wave sleep (SWS). PS architecture and waking-state erections remained unchanged after lesion in all groups. These data identify an essential role of the LPOA in both PS-related erectile mechanisms and SWS generation. Moreover, higher erectile mechanisms appear to be context-specific because LPOA lesioning selectively disrupted PS-related erections while leaving waking-state erections intact.     

Temporal relationship between nocturnal erections and rapid eye movement episodes in healthy men

The exact temporal relationship between spontaneous nocturnal erections and rapid eye movement (REM) sleep was studied in healthy men with the aim of creating a basis for a more sophisticated analysis of nocturnal erection measurements in physiological research and clinical applications. The vast majority of erectile events was coupled to REM episodes, where the latency between the beginning of erections and REM episodes showed a large variability. Moreover, a correlation analysis revealed a highly significant decrease of the latency over the course of the night. The time variant properties of the coupling between erections and REM sleep point to more complex dynamics of the central control of erections with regard to sleep regulation, indicating that REM sleep and REM-related erections are not completely interdependent. Beside the possibility of obtaining further insight into the physiological mechanisms underlying erectile function, the consideration of dynamic aspects in the assessment of nocturnal erection measurements might have potential clinical implications regarding both the diagnosis and the evaluation of therapies for erectile dysfunction.     

Sleep-related erection neurophysiology: a journey of discovery

Michel Jouvet established a tradition of sleep neurophysiology that inspired several generations of sleep researchers. When I arrived in his laboratory in 1991, it was known that erection cycles occur during rapid eye movement (REM) sleep in humans. However, it was not known if such erections in sleep occurred in other species, or how REM-related erections were controlled. Employing the classical techniques and systematic approach of Jouvet and his team, I embarked on a journey of discovery. Not only were fundamental principles of REM-related erectile control identified, such as the critical role of the lateral preoptic area in the forebrain, but I also gained a deep appreciation of the scientific approach in the Jouvet tradition. Such insights passed on to his many students, together with a lifetime of friendships and collaborations, have left an indelible mark on our field.     

Quantification of electromyographic activity during sleep: a phasic electromyographic metric.

Recording of electromyographic (EMG) activity is considered essential for defining rapid eye movement (REM) sleep and for quantifying certain types of movements in sleep, such as periodic leg movements in sleep (PLMS). However, routine analyses of EMG activity beyond such purposes is performed rarely and quantified seldom, and normative data are lacking. In this study, the authors examined systematic application of a visual scoring system for short-duration (approximately 100-millisecond) phasic EMG activity recorded from five different muscle groups (submentalis, left/right anterior tibialis, left/right brachioradialis) recorded from two different age groups of normal subjects and a group of patients with Parkinson's disease. Quantification of this activity was labeled as a phasic electromyographic metric (PEM). PEM data were compiled separately by REM and non-REM sleep. Results indicated that PEM is a normal part of REM sleep in all muscle groups, more specifically constituting about 5% (SD = 3.1%) of 2.5-second intervals of REM sleep in the mentalis in healthy young adults. It occurs at higher rates in patients with Parkinson's disease, and its quantification in the legs may be influenced to some degree by the presence of PLMS. PEM may be a useful metric amenable to quantification with digital techniques. It may have particular relevance for the identification of neurodegenerative conditions in which disinhibition of midbrain dopaminergic pathways results in excessive motor discharge during sleep.     

Olivopontocerebellar degeneration, abnormal sleep, and REM sleep without atonia

Polygraphic studies during sleep performed in two patients with olivopontocerebellar degeneration (OPCD) revealed an abnormal control of muscle tone. It was demonstrated by bursts of EMG activity during sleep and progressive disappearance of muscle atonia during sleep. Muscle atonia disappeared during rapid eye movement (REM) sleep, permitting movements and expression of feelings probably associated with REM sleep-related oneiric activity. Patients, unaware of their nocturnal sleep disturbance, complained only of the resulting daytime tiredness and sleepiness.     

Evaluation of impotence. Monitoring periodic penile erections during sleep

The monitoring of periodic penile erections during sleep has helped alter the understanding and treatment of impotent patients. The reasons why this has occurred, the procedures used in monitoring sleep erections, and the validation of the procedures are reviewed.     

Electroencephalographic sleep abnormalities in schizophrenia. Relationship to positive/negative symptoms and prior neuroleptic treatment.

Polysomnographic abnormalities in schizophrenia are not well characterized and their associations with schizophrenic symptomatology have not been adequately assessed. To address these issues, we recorded electroencephalographic sleep in 20 drug-naive schizophrenics, 20 drug-free but previously medicated schizophrenics, and 15 normal controls. Drug-naive and previously medicated patients had significantly greater impairment of sleep continuity and shorter rapid eye movement latency when compared with controls. In the previously medicated group, findings were significantly influenced by duration of drug-free status. Rapid eye movement latency was inversely correlated with the severity of negative symptoms (r = -.52) but was unrelated to depressive symptoms. Slow-wave sleep did not differ between schizophrenic patients and normal controls and was unrelated to any clinical parameter. Mechanisms underlying the observed associations between rapid eye movement sleep abnormalities and negative symptoms in the acute phase of schizophrenic illness need to be explored.     

Quantitative analysis of surface EMG activity of cranial and leg muscles across sleep stages in human.

OBJECTIVE: The aim of this study was to make a quantitative analysis of the changes in cranial and limb muscle activity from wakefulness to light and deep sleep stages and during rapid eye movement (REM) sleep of normal subjects. METHODS: Polysomnographic recordings were made of the sleep of 9 healthy human subjects, including electromyograms of the suprahyoid, temporalis and masseter cranial muscles and the anterior tibialis limb muscle. Quantitative assessments of EMG activity were carried out with root mean square (RMS) and frequency-spectral analysis (FSA) methods. RESULTS: From wakefulness to sleep, a significant reduction (-25.2 to -71.2%; P < 0.01) was observed in EMG activity (for both RMS and FSA) of the 3 cranial muscles using both methods of analysis. The EMG activity of suprahyoid muscle further decreased from non-REM to REM sleep (-17.8 to -43.0%; P < 0.01). In contrast, the EMG activity of the anterior tibialis muscle was only slightly reduced across sleep stages and did not further reduce during REM sleep. During REM sleep, all the 4 muscles maintained minimal activity. CONCLUSIONS: The maintenance of muscle activity during REM sleep suggests that a minimal level of activity is required to preserve physiological functions (e.g. airway patency, posture) related to homeostasis and bodily protection. SIGNIFICANCE: This study suggests that quantitative sleep EMG analysis is important for understanding the mechanisms of sleep-related movement disorders or when objective assessment of changes in EMG activity are needed for diagnostic purposes or for the assessment of drug efficiency.     

Loss of REM sleep features across nighttime in REM sleep behavior disorder

ObjectivesMelatonin is a chronobiotic treatment which also alleviates rapid eye movement (REM) sleep behavior disorder (RBD). Because the mechanisms of this benefit are unclear, we evaluated the clock-dependent REM sleep characteristics in patients with RBD, whether idiopathic (iRBD) or associated with Parkinson's Disease (PD), and we compared findings with PD patients without RBD and with healthy subjects.MethodsAn overnight videopolysomnography was performed in ten iRBD patients, ten PD patients with RBD (PD + RBD+), ten PD patients without RBD (PD + RBD−), and ten controls. The rapid eye movement frequency per minute (REMs index), the tonic and phasic electromyographic (EMG) activity of the levator menti muscle, and the duration of each REM sleep episode were evaluated. A generalized linear model was applied in each group, with the REM sleep cycle (four ordinal levels) as the dependent variable, as a function of REMs index, REM sleep duration, and tonic and phasic EMG activity.ResultsFrom the first to the fourth sleep cycle, REM sleep duration progressively increased in controls only, REMs index increased in subjects without RBD but not in patients with RBD, whether idiopathic or associated with PD, whereas tonic and phasic EMG activity did not change.ConclusionsPatients with PD or iRBD lost the physiologic nocturnal increase in REM sleep duration, and patients with RBD (either with or without PD) lost the increase of REMs frequency across the night, suggesting an alteration in the circadian system in RBD. This supports the hypothesis of a direct effect of melatonin on RBD symptoms by its chronobiotic activity.     

Effect of Sleep-Disordered Breathing During Rapid Eye Movement Sleep and Non-Rapid Eye Movement sleep on Acute Ischemic Stroke

ObjectivesSleep-disordered breathing adversely impacts stroke outcomes. We investigated whether sleep-disordered breathing during rapid eye movement sleep and non-rapid eye movement sleep differentially influenced stroke outcomes.Materials and MethodsAcute ischemic stroke patients who finished polysomnography within 14 days of stroke onset from April 2010 to August 2018 were reviewed. Patients were divided into four groups according to apnea-hypopnea index during rapid eye movement sleep and non-rapid eye movement sleep. The modified Rankin Scale was used to evaluate short-term outcome. During January and April 2019, another follow-up was performed for long-term outcomes, including stroke-specific quality-of-life scale, modified Rankin Scale, stroke recurrence and death.ResultsOf 140 patients reviewed, 109 were finally recruited. Although patients with sleep-disordered breathing during non-rapid eye movement sleep only and with sleep-disordered breathing during both rapid eye movement sleep and non-rapid eye movement sleep had higher apnea-hypopnea indices and more disrupted sleep structures, short-term and long-term outcomes did not significantly different between four groups. In Logistic regression analysis, apnea-hypopnea index (p = 0.013, OR 1.023, 95%CI 1.005–1.042) was found independently associated with short-term outcome. Rapid eye movement sleep latency (p = 0.045, OR 0.994, 95%CI 0.987–1.000) was found independently associated with quality of life. Apnea-hypopnea indices during rapid eye movement sleep or non-rapid eye movement sleep were not significantly associated with short-term or long-term outcomes.ConclusionsApnea-hypopnea index is an independent risk factor of short-term outcome of acute ischemic stroke while sleep-disordered breathing during rapid eye movement sleep and non-rapid eye movement sleep do not affect stroke outcomes differently.     

Rapid eye movement latency in children and adolescents

Rapid eye movement sleep distribution changes during development, but little is known about rapid eye movement latency variation in childhood by age, sex, or pathologic sleep states. We hypothesized that: (1) rapid eye movement latency would differ in normal children by age, with a younger cohort (1-10 years) demonstrating shorter rapid eye movement latency than an older group (>10-18 years); (2) rapid eye movement latency in children would differ from typical adult rapid eye movement latency; and (3) intrinsic sleep disorders (narcolepsy, pediatric obstructive sleep apnea syndrome) would disrupt normal developmental patterns of rapid eye movement latency. A retrospective chart review included data from clinic visits and of rapid eye movement latency and other parameters measured by overnight polysomnography. Participants included 98 control children, 90 children with obstructive sleep apnea syndrome, and 13 children with narcolepsy. There were no statistically significant main effects of age category or sex on rapid eye movement latency. Rapid eye movement latency, however, exhibited a significant inverse correlation with age within the older control children. Healthy children exhibited rapid eye movement latencies significantly longer than adults. Normal control patients demonstrated significantly longer rapid eye movement latency than obstructive sleep apnea syndrome and narcolepsy patients.     

The first-night effect may last more than one night.

The first-night effect in sleep polysomnographic studies is usually considered to last for one night. However, a few observations have indicated that variables associated to rapid eye movement sleep take longer to stabilize. Notwithstanding, current opinion holds that second nights of recording can be used without restriction for research and clinical purposes. The goal of this study was to describe the dynamics of habituation to polysomnography in optimal conditions. Twenty-six young, carefully screened, healthy subjects were recorded in their home for four consecutive full polysomnographies. Repeated measures ANOVA were applied. Between the two first nights, while there were no differences in sleep duration in non-rapid eye movement sleep, marked modifications in corresponding spectral power were observed. The dynamics of adaptation of rapid eye movement sleep appeared to be a process extending up to the fourth night. Similar dynamics in NREMS and REMS homeostasis have been observed in sleep deprivation studies, and it appears that the same mechanisms may be responsible for the FNE. The longer habituation process of REMS in particular has important implications for sleep research in psychiatry.     

Temporal coupling of rapid eye movements and cerebral activities during REM sleep

ObjectivesWe investigated event-related potentials time locked to the onset and offset of rapid eye movements during rapid eye movement (REM) sleep.MethodNine healthy university students participated in this study. Data were collected in a sleep laboratory. Rapid eye movements during REM sleep were recorded during natural nocturnal sleep. Saccades during wakefulness were recorded during a visually triggered task. Event-related potentials were averaged, time-locked to the onset and offset of eye movements.ResultsDuring REM sleep, a lambda-like response occurred over the occipital region, time-locked to the offset of rapid eye movements (similar to what occurs during wakefulness). Moreover, we found that a positive potential (P200r) occurred at about 200 ms, with the maximal amplitude over the central region and time-locked to the onset of rapid eye movements during REM sleep; this potential was not observed during wakefulness.ConclusionsDuring REM sleep, the P200r occurs with the start of rapid eye movements, and then the lambda-like response occurs after termination of the movements.SignificanceWe demonstrated temporal coupling of rapid eye movements and cerebral activities during REM sleep. These activities might provide a useful basis for future investigations of brain functions during REM sleep.     

A note on the occurrence of unusual electroencephalographic sleep patterns in selected normal children.

Polysomnographic recordings were performed in 50 children free from any familial or personal history of seizure or neurologic diseases to evaluate the frequency of epileptiform and unusual electroencephalographic patterns in a normal population. A 9-year-old boy exhibited focal spikes that became bilateral with a density of 24% to 32% during slow wave sleep, and another boy showed a few spikes during slow wave sleep. In seven cases, 14- and 6-Hz rhythms were recorded, mostly in rapid eye movement sleep. A right rhythmic and temporal discharge was observed in one girl. Epileptiform electroencephalographic patterns are not infrequent, and 14- and 6-Hz rhythms during rapid eye movement sleep are common in normal children.     

Automated determination of wakefulness and sleep in rats based on non-invasively acquired measures of movement and respiratory activity

The current standard for monitoring sleep in rats requires labor intensive surgical procedures and the implantation of chronic electrodes which have the potential to impact behavior and sleep. With the goal of developing a non-invasive method to determine sleep and wakefulness, we constructed a non-contact monitoring system to measure movement and respiratory activity using signals acquired with pulse Doppler radar and from digitized video analysis. A set of 23 frequency and time-domain features were derived from these signals and were calculated in 10 s epochs. Based on these features, a classification method for automated scoring of wakefulness, non-rapid eye movement sleep (NREM) and REM in rats was developed using a support vector machine (SVM). We then assessed the utility of the automated scoring system in discriminating wakefulness and sleep by comparing the results to standard scoring of wakefulness and sleep based on concurrently recorded EEG and EMG. Agreement between SVM automated scoring based on selected features and visual scores based on EEG and EMG were approximately 91% for wakefulness, 84% for NREM and 70% for REM. The results indicate that automated scoring based on non-invasively acquired movement and respiratory activity will be useful for studies requiring discrimination of wakefulness and sleep. However, additional information or signals will be needed to improve discrimination of NREM and REM episodes within sleep.     

Yawning behavior in male rats is associated with decreases in in vivo DOPAC efflux from the caudate nucleus

Young adult male rats were implanted with a push-pull cannula aimed at the dorsal and rostral areas of the caudate nucleus. Perfusate samples were collected at two-minute intervals for approximately one hour and assayed for DOPAC concentrations. Simultaneously, yawning, penile erections and grooming behavior were recorded. Yawns were induced by systemic prolactin or apomorphine injections. While mean DOPAC efflux was elevated following prolactin (PRL) and apomorphine decreased mean DOPAC efflux as expected, yawns and penile erections induced by both compounds were associated with rapid momentary decreases in DOPAC efflux in these living animals. Although yawning was associated with significant decreases in DOPAC output, not every momentary DOPAC decrease was associated with a yawn, suggesting that the 'yawning generator' most likely requires additional inputs for the expression of a yawn.