Nocturnal penile tumescence

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Nocturnal penile tumescence (NPT) is a spontaneous erection of the penis during sleep or when waking up. Along with nocturnal clitoral tumescence, it is also known as sleep-related erection. (Colloquially, the term morning wood (or less commonly, morning glory) is also used, [1] although this is more commonly used to refer specifically to an erection beginning during sleep and persisting into the period just after waking.) Men without physiological erectile dysfunction or severe depression [2] experience nocturnal penile tumescence, usually three to five times during a period of sleep, typically during rapid eye movement sleep. [3] Nocturnal penile tumescence is believed to contribute to penile health. [4]

Contents

Mechanism

The cause of nocturnal penile tumescence is not known with certainty. In a wakeful state, in the presence of mechanical stimulation with or without an arousal, erection is initiated by the parasympathetic division of the autonomic nervous system with minimal input from the central nervous system. [5] Parasympathetic branches extend from the sacral plexus of the spinal nerves into the arteries supplying the erectile tissue; upon stimulation, these nerve branches release acetylcholine, which in turn causes release of nitric oxide from endothelial cells in the trabecular arteries, that eventually causes tumescence. Bancroft (2005) hypothesizes that the noradrenergic neurons of the locus ceruleus in the brain are perpetually inhibitory to penile erection, and that the cessation of their discharge that occurs during rapid eye movement sleep may allow testosterone-related excitatory actions to manifest as nocturnal penile tumescence. [6] Suh et al. (2003) recognizes that in particular the spinal regulation of the cervical cord is critical for nocturnal erectile activity. [7]

The nerves that control one's ability to have a reflex erection are located in the sacral nerves (S2-S4) of the spinal cord. [8] Evidence supporting the possibility that a full bladder can stimulate an erection has existed for some time and is characterized as a 'reflex erection'. [9] A full bladder is known to mildly stimulate nerves in the same region. The possibility of a full bladder causing an erection, especially during sleep, is perhaps further supported by the beneficial physiological effect of an erection inhibiting urination, thereby helping to avoid nocturnal enuresis [ citation needed ]. However, given females have a similar phenomenon called nocturnal clitoral tumescence, prevention of nocturnal enuresis (bed-wetting) is not likely a sole supporting cause. [10]

In a study published in 1972, [11] during puberty, the average tumescence time per night was 159 min; average REM sleep time was 137 min. Average simultaneous REM sleep and penile tumescence per night was 102 min. Study subjects averaged 6.85 tumescence episodes/night, and, of these, 5.15 occurred during a REM sleep period. Tumescence episodes during REM averaged 30.8 min in duration, whereas episodes which occurred when no REM was present averaged 11.75 min. Study subjects had at least four REM periods per night and at least three tumescence episodes.

In another study of healthy older people published in 1988, frequency and duration of nocturnal penile tumescence decreased progressively with age independent of variations in sleep. In contrast to younger age groups, the majority of those above age 60 did not have full sleep erections even though they and their partners reported regular intercourse. [12]

Unlike physiological penile tumescence, sleep-related painful erections (SRPE) and stuttering priapism (SP) are much rarer pathological erections, resulting in poor sleep and daytime tiredness, and long term cardiovascular morbidity. [13] SRPE is a rare parasomnia consisting of nocturnal penile tumescence accompanied by pain that awakens the individual. [14] It occurs predominantly during REM sleep, without an apparent underlying illness or penile anatomic abnormalities. On the contrary, stuttering priapism can occur spontaneously at any time of the day, but more commonly so during REM sleep. SP is a subtype of ischemic priapism that is characterized by recurrent, self-limiting, painful erections that often require maneuvers (compression, cold packs or a cold shower, voiding, or exercise, etc.) to aid detumescence. In ischemic priapism, most of the penis is hard; however, the glans penis is not. Much rarer priapism is secondary to blunt trauma to the perineum or penis, with laceration of the cavernous artery, which can generate an arterial-lacunar fistula resulting in a high blood flow state, hence the tumescence. Tumescence lasting for more than four hours is a medical emergency. [15] At the time being, no treatment consensus for SRPE has been established. Baclofen tablets taken before sleep is the most commonly used medication, having a tolerable profile of adverse effects. [14]

Diagnostic value

The existence and predictability of nocturnal tumescence is used by sexual health practitioners to ascertain whether a given case of erectile dysfunction is psychological or physiological in origin. [3] A patient presenting with erectile dysfunction is fitted with an elastic device to wear around his penis during sleep; the device detects changes in girth and relays the information to a computer for later analysis. If nocturnal tumescence is detected, then the erectile dysfunction is presumed to be due to a psychosomatic illness such as sexual anxiety; if not, then it is presumed to be due to a physiological cause. [3]

Nocturnal penile tumescence testing

Regularly, those who experience erectile dysfunction are given a nocturnal penile tumescence test, usually over a three-day period. Such a test detects the presence of an erection occurring during sleep using either:

  1. a small portable computer connected to two bands placed around the shaft of the penis which records penile tumescence,
  2. a band of paper tape with perforations (similar to coil postage stamps) that is fit snugly around the shaft of the penis and will break at the perforations during penile tumescence.

The goal of nocturnal penile tumescence testing is to determine whether one can experience an erection while sleeping after reporting that they are unable to experience an erection while awake. On average, one has 3–5 episodes of NPT each night, and each episode lasts 30–60 minutes, although the duration is reduced with advanced age. [16] If one does obtain an erection while sleeping, but cannot obtain one while awake, a psychological cause or a medication side effect is usually suspected. Otherwise, if one does not obtain an erection in either state, a physiological cause is usually suspected.

See also

Related Research Articles

<span class="mw-page-title-main">Clitoris</span> Organ at the top of the vulva

The clitoris is a female sex organ present in mammals, ostriches, and a limited number of other animals. In humans, the visible portion – the glans – is at the front junction of the labia minora, above the opening of the urethra. Unlike the penis, the male homologue (equivalent) to the clitoris, it usually does not contain the distal portion of the urethra and is therefore not used for urination. In most species, the clitoris lacks any reproductive function. While few animals urinate through the clitoris or use it reproductively, the spotted hyena, which has an especially large clitoris, urinates, mates, and gives birth via the organ. Some other mammals, such as lemurs and spider monkeys, also have a large clitoris.

Erectile dysfunction (ED), also referred to as impotence, is a form of sexual dysfunction in males characterized by the persistent or recurring inability to achieve or maintain a penile erection with sufficient rigidity and duration for satisfactory sexual activity. It is the most common sexual problem in males and can cause psychological distress due to its impact on self-image and sexual relationships. Majority of ED cases are attributed to physical risk factors and predictive factors. These factors can be categorized as vascular, neurological, local penile, hormonal, and drug-induced. Notable predictors of ED include aging, cardiovascular disease, diabetes mellitus, high blood pressure, obesity, abnormal lipid levels in the blood, hypogonadism, smoking, depression, and medication use. Approximately 10% of cases are linked to psychosocial factors, encompassing conditions like depression, stress, and problems within relationships.

<span class="mw-page-title-main">Priapism</span> Medical condition where an erection lasts excessively long

Priapism is a condition in which a penis remains erect for hours in the absence of stimulation or after stimulation has ended. There are three types: ischemic (low-flow), nonischemic (high-flow), and recurrent ischemic (intermittent). Most cases are ischemic. Ischemic priapism is generally painful while nonischemic priapism is not. In ischemic priapism, most of the penis is hard; however, the glans penis is not. In nonischemic priapism, the entire penis is only somewhat hard. Very rarely, clitoral priapism occurs in women.

<span class="mw-page-title-main">Cock ring</span> Sexual device

A cock ring or cockring is a ring worn around the penis, usually at the base. The primary purpose of wearing a cock ring is to restrict the flow of blood from the erect penis to produce a stronger erection or to maintain an erection for a longer period of time. They are sometimes used as medical devices, on their own or in conjunction with a penis pump to assist in the management of erectile dysfunction. Genital adornment is another purpose, as is repositioning the genitals to provide an enhanced appearance.

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Anorgasmia is a type of sexual dysfunction in which a person cannot achieve orgasm despite adequate stimulation. Anorgasmia is far more common in females than in males and is especially rare in younger men. The problem is greater in women who are post-menopausal. In males, it is most closely associated with delayed ejaculation. Anorgasmia can often cause sexual frustration.

Penile plethysmography (PPG) or phallometry is a measurement of blood flow to the penis, typically used as a proxy for measurement of sexual arousal. The most commonly reported methods of conducting penile plethysmography involves the measurement of the circumference of the penis with a mercury-in-rubber or electromechanical strain gauge, or the volume of the penis with an airtight cylinder and inflatable cuff at the base of the penis. Corpora cavernosa nerve penile plethysmographs measure changes in response to inter-operative electric stimulation during surgery. The volumetric procedure was invented by Kurt Freund and is considered to be particularly sensitive at low arousal levels. The easier to use circumferential measures are more widely used, however, and more common in studies using erotic film stimuli. A corresponding device in women is the vaginal photoplethysmograph.

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Tumescence is the quality or state of being tumescent or swollen. Tumescence usually refers to the normal engorgement with blood of the erectile tissues, marking sexual excitation, and possible readiness for sexual activity. The tumescent sexual organ in males is the penis and in females is the clitoris and other parts of the genitalia like the vestibular bulbs. Arteries in the penis dilate to increase blood volume.

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<span class="mw-page-title-main">Erection</span> Physiological phenomenon involving the hardening and enlargement of the penis

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<span class="mw-page-title-main">Clitoral erection</span> Physiological phenomenon involving the engorgement of the clitoris

Clitoral erection is a physiological phenomenon where the clitoris becomes enlarged and firm.

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<span class="mw-page-title-main">Glans insufficiency syndrome</span> Medical condition

Glans insufficiency syndrome, also known as the soft glans, cold glans, or glans insufficiency, is a medical condition that affects male individuals. This condition is characterized by the persistent inability of the glans penis to achieve and maintain an erect or turgid state during sexual arousal, remaining soft and cold. This condition can have an impact on a person's sexual function, including decreased sensitivity, difficulty in maintaining an erection, and overall quality of life.

References

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  2. ↑ Thase ME, Reynolds CF, Jennings JR, Frank E, Howell JR, Houck PR, et al. (May 1988). "Nocturnal penile tumescence is diminished in depressed men". Biological Psychiatry. 24 (1): 33–46. doi:10.1016/0006-3223(88)90119-9. PMID   3370276. S2CID   24315629.
  3. 1 2 3 Felson S (7 November 2020). "Tests for Erection Problems". WebMD, Inc. Retrieved 2007-03-03.
  4. ↑ Alexander B (October 2010). "Why guys rise and, well, rise in the morning?". The Body Odd. NBC News.
  5. ↑ "SCI Fact Sheets - Spinal Cord Injury Model System". Heersink School of Medicine. The University of Alabama at Birmingham (UAB).
  6. ↑ Bancroft J (September 2005). "The endocrinology of sexual arousal". The Journal of Endocrinology. 186 (3): 411–427. doi: 10.1677/joe.1.06233 . PMID   16135662.
  7. ↑ Suh DD, Yang CC, Clowers DE (January 2003). "Nocturnal penile tumescence and effects of complete spinal cord injury: possible physiologic mechanisms". Urology. 61 (1): 184–189. doi: 10.1016/S0090-4295(02)02112-X . PMID   12559293.
  8. ↑ Klebine P, Lindsey L (May 2007). "Sexual Function for Men with Spinal Cord Injury". Spinal Cord Injury Information Network. University of Alabama at Birmingham. Archived from the original on 2013-09-06. Retrieved 2011-12-17.
  9. ↑ "Nervous system control of the male reproductive system". Spinal Hub. Retrieved 2018-01-09.
  10. ↑ Beale S (Aug 2016). "Why Do Men Get Erections in the Morning". IFL Science. Retrieved 2016-12-03.
  11. ↑ Karacan I, Hursch CJ, Williams RL, Littell RC (June 1972). "Some characteristics of nocturnal penile tumescence during puberty". Pediatric Research. 6 (6): 529–537. doi: 10.1203/00006450-197206000-00001 . PMID   4340042. S2CID   10758883.
  12. ↑ Schiavi RC, Schreiner-Engel P (September 1988). "Nocturnal penile tumescence in healthy aging men". Journal of Gerontology. 43 (5): M146–M150. doi:10.1093/geronj/43.5.m146. PMID   3418036.
  13. ↑ Johnson M, McNeillis V, Gutbier J, Eaton A, Royston R, Johnson T, et al. (September 2022). "Differences in polysomnographic, nocturnal penile tumescence and penile doppler ultrasound findings in men with stuttering priapism and sleep-related painful erections". International Journal of Impotence Research. 34 (6): 603–609. doi:10.1038/s41443-021-00462-3. PMC   9485052 . PMID   34389802. S2CID   236993535.
  14. 1 2 Abdessater M, Kanbar A, Zugail AS, Al Hammadi A, Guillonneau B, Beley S (December 2019). "Sleep related painful erection: an algorithm for evaluation and management". Basic and Clinical Andrology. 29 (1): 15. doi: 10.1186/s12610-019-0095-5 . PMC   6894200 . PMID   31844522.
  15. ↑ Podolej GS, Babcock C (January 2017). "Emergency Department Management Of Priapism". Emergency Medicine Practice. 19 (1): 1–16. PMID   28027457.
  16. ↑ Bella AJ, Lue TF (12 December 2007). "Male Sexual Dysfunction". In Tanagho EA, McAninch JW (eds.). Smith's General Urology (17th ed.). McGraw Hill Professional. pp. 589–. ISBN   978-0-07-159331-1.

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