Under normal circumstances, men have nocturnal erections from infancy to adulthood, and nocturnal erection is a physiological phenomenon. Since nocturnal erection occurs at night and basically eliminates the influence of psychological factors, the normal or not of nocturnal erection is often used clinically to determine whether impotence is psychological or organic. 1. How many kinds of erections does the penis have under normal circumstances? The mechanism of penile erection is the expansion and filling of the blood sinuses of the penile corpus cavernosum, and this process is governed by parasympathetic nerves. There are three types of penile erection: psychological erection, reflex erection and nocturnal erection. (1) Psychogenic erection is an erection caused by purely psychological desire (e.g. sexual fantasy); psychogenic erection can be caused by mental imagination alone without seeing or touching the female partner. (2) Reflex erection An erection caused by sensory stimulation (including seeing the other person’s face, hearing the other person’s voice and touching the other person’s body). ③Nocturnal erection is the erection of the penis in the state of sleep. 2. What is nocturnal erection? A nocturnal erection is an erection of the penis that occurs while a man is sleeping. Generally, men will have an erection on average 3-6 times a night. A nocturnal erection is an erection that occurs while sleeping and is completely free of anxiety and tension, so it can better reflect the quality of the penis erection. If you have a bad erection normally or during sex, but your nocturnal erection is found to be good during the examination, the cause of erectile dysfunction is likely to be psychological. The mechanism of nocturnal penile erection is still unclear and may be related to reduced sympathetic excitability or increased parasympathetic excitability during nighttime sleep. 3.If the erection at night is normal, what can it indicate? Nocturnal erection is different from daytime erection. Nocturnal erection occurs in the absence of sexual stimulation (including direct stimulation to the penis or visual and other stimulation), so nocturnal erection is not disturbed by psychological factors (such as tension or low self-confidence). Medical studies have found that nocturnal erections can occur even in the absence of consciousness; for example, vegetative people can have very good nocturnal erections. If the nocturnal erection is very good, it is at least an indication that the penile corpus cavernosum itself is not faulty. The cause of impotence is outside the penis, such as a sympathetic excitability problem, or a problem with the central nervous system. The hardening and weakening of the penis are governed by the parasympathetic and sympathetic nerves respectively, and the sympathetic and parasympathetic nerves have a reciprocal relationship. The sympathetic nerve activity is weaker under sleep conditions, while the parasympathetic nerve activity is relatively stronger. If the erection is good at night but not during the day, it means that the excitability of the sympathetic nerve is stronger during the day and exceeds the activity of the parasympathetic nerve, so the ability of the penis to weaken exceeds the ability to erect, and impotence occurs. 4. What does it mean if the erection is not normal at night? A problem with any of the components involved in penile erection can affect nocturnal erections. Nocturnal erections may be abnormal due to diseases of the penile corpus cavernosum itself such as insufficient arterial blood supply or venous leakage, damage to the nerves that govern penile erection, arteriovenous malformations, hormone deficiencies, and various chronic diseases such as diabetes. Of course, whether the nocturnal erectile function indicator is normal or not is only the most primary indicator for clinical diagnosis of impotence, and further comprehensive examination is usually needed to find the cause. 5.How to check nocturnal erection? At present, there are special testing devices to measure nocturnal erections. The size of the monitoring device is relatively small (such as the size of a soap) and lightweight, so it can be monitored at home or in the hospital. A sensing electrode is wrapped around the penis at bedtime to feel and record the erection during the night, including the number of erections, hardness, duration of erection and changes in circumference during erection. The test can be interfered with by external factors that can affect the effectiveness of monitoring, so sometimes three consecutive monitoring sessions are required. Before the introduction of the monitoring device, the stamp test was used clinically, i.e., an unripped stamp with joint holes was used and stuck around the penis at the overlap before going to bed, and if there was a tear at the hole of the stamp when waking up in the morning, it meant that there had been an erection at night. Since the erection hardness, erection duration and number cannot be measured, it is not very helpful for clinical diagnosis. 6. Notes on nocturnal erection examination. ①The quality of the patient’s sleep at night is closely related to the test results, because the psychological factors affecting the erection of the penis can be removed only when the patient is asleep, so if the patient’s sleep quality is poor at night, it will affect the test results. ②Factors such as patients turning over at night during sleep, or frequent turning over, or getting up to urinate at night can affect the nocturnal erection monitoring, which can sometimes cause false or incorrect results, so it must be analyzed in detail when analyzing the results. ③The test can suggest to some extent whether the impotence is vascular, but it cannot confirm the diagnosis. Further color Doppler ultrasonography and contrast examination are required for a definite diagnosis. ④Affected by drugs For example, taking erection-boosting drugs, or sedative drugs, anti-anxiety and depression drugs, or anti-androgen drugs can affect the monitoring results, and a comprehensive analysis is needed.