Nocturnal Penile Tumescence: Why Do Men Wake Up with an Erection?

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Nocturnal Penile Tumescence: Why Do Men Wake Up with an Erection?

How many times have you wondered why men wake up with an erection? Popularly known in slang as morning wood – there are many misconceptions about how these could be due to being in a state of sexual arousal. But we are here to drop some scientific truth bombs. Guess what?

Getting morning wood or penile erection is perfectly normal and natural. And no, it is not necessarily caused by sexual arousal or wet dreams.

Representational image only. Photo Credit: Freepik

The medical term for this is nocturnal penile tumescence (NPT). Simply calling it morning wood can be misleading because, during an NPT episode, penises can become erect and flaccid several times in a single night. Yes, it can be particularly noticeable on waking up. Scientific studies suggest that these morning penile erections are involuntary and can affect everyone. Did you know even women get clitoral erections while asleep?

Don’t shy away from discussing this. Having regular episodes of NPT show that your nerves and blood supply to the penis are working optimally. It is a sign of good reproductive health. Studies suggest a healthy male has between three to five erections over eight hours of sleep. And each of these can last up to 30 minutes. So, men, expect to get hard three to five times per night. What if this doesn’t happen? It could be your body’s biofeedback pointing to an underlying condition. It could range from a nerve malfunction, arterial disease, hypertension, diabetes, low testosterone, depression, anxiety, and so on. Let’s delve into what causes these erections.

It’s not you. It’s your parasympathetic nervous system.

Understand this. Nocturnal penile erections happen during the rapid eye movement (REM) sleep phase. It begins 60 to 90 minutes after you sleep and is the phase where you dream vividly when certain areas of your brain are activated.

It stimulates your parasympathetic system (rest and digest mode). It affects the sacral nerve, a cluster of five nerves in your lower back that controls erections.

There are many theories around why men get NPT. Let’s have a look.

  • Researchers suggest that entering the REM sleep phase affects and slows down the production of neurotransmitters. One such neurotransmitter that is responsible for keeping the penis relaxed is norepinephrine. It constricts the penis blood cells to ensure you don’t have a boner 24×7. What happens when the production of norepinephrine reduces? It can lead to testosterone-related excitement and increase blood flow to your penis, causing an erection.
  • Similarly, another scientific school of thought suggests that your body produces more nitric oxide during the REM sleep phase. Nitric oxide is responsible for relaxing the blood vessels of the penis, thus allowing more blood to rush to it and lead to an erection.

Who experiences NPT?

Boys as young as 6 to 8 years old and men in their 60s and 70s experience NPT episodes. But yes, their frequency reduces as you age and start experiencing erectile dysfunction issues. Remember, this change will happen over time, gradually as your hormone levels shift. If you are someone who has a sudden drop in the number of NPT episodes, you need to consult a doctor. It could be a sign of another underlying health condition.

What are the reasons for the loss of NPT?

  • High cholesterol and blood pressure damage your blood vessels by affecting elasticity and making it difficult for them to expand. It can constrict the blood flow into the penis, thus affecting NPT.
  • Poor quality sleep. Studies suggest that consistently poor sleep patterns affect the frequency of NPT.
  • Another study suggests that having sex less than once a week can reduce your NPT episodes and increase your risk of erectile dysfunction. Having sex three times a week can help.

Can medications reduce the frequency of NPT episodes? YES.

Some medications can make it difficult for you to have or maintain an erection. They can reduce the frequency or even stop NPT episodes in extreme cases.

  • Antidepressants
  • High blood pressure medication
  • Hormonal medications
  • Seizure medications
  • Chemotherapy drugs
  • Muscle relaxers
  • Arrhythmia medications
  • Diuretics
  • Histamine H2 agonists (used to treat ulcers)

Reduced episodes or loss of NPT could point to other health and lifestyle conditions that affect erectile function. Some of these include:

  • High cholesterol levels
  • Chronic stress
  • Type 2 diabetes, Prediabetes
  • Hypertension
  • Depression
  • Sleep disorders
  • Cardiovascular diseases
  • Hormonal imbalances
  • Side effects of medication
  • Metabolic syndrome
  • Poor lifestyle
  • Poor emotional health

Here’s what scientific studies suggest

  • Men with less than one-morning erection a week are 2.5 times more likely to get erectile dysfunction than men experiencing two or three-morning erections per week.
  • To get an erection, sufficient blood needs to rush to your penis. And for this, your endothelial cells need to relax, allowing the arteries to widen and let the blood flow. Hardening of the arteries or atherosclerosis begins by affecting these first. So, loss of NPT could also be a symptom.
  • Men with erectile dysfunction are 45% more likely to develop heart disease within five years. The same increase in risk is associated with smoking or high cholesterol.
  • Most doctors believe erectile dysfunction if diagnosed early, can help men avert heart disease by making consistent lifestyle changes.
  • Studies also link erectile dysfunction with chronic inflammation and respiratory, gastrointestinal, and endocrine disorders.
    Tobias Köhler (M.D, M.P.H) suggests that loss of NPT could cause the muscles in your penis to contract over time and shorten its length.

Is your NPT pointing to a physical or psychological root cause?

If you are unable to get or maintain an erection during sexual activity despite trying, your doctors may rule out insufficient blood flow or nerve responses. In this case, it could point to a psychological issue. Is it performance anxiety or depression? Address the root cause.

Is your emotional health affecting your NPT? Photo Credits: Freepik

A simple home test for NPT

All you need is a thin plastic ring. Secure it around a flaccid penis. Check if the erections that occur at night can bust apart the restriction. If the ring is unmoved, it means your erections did not happen or were not vigorous enough.

When should I see a doctor?

  • A sudden drop in the NPT frequency
  • A complete loss of NPT
  • If you start new medications and notice a drop in NPT frequency
  • Painful erections or NPT
  • If your erection does not go away even after four hours. It could cause tissue damage in the penis and lead to other sexual dysfunction issues.
  • Invest in annual checkups and seek professional help when your body signals you, regardless of age.

And if paying more attention to your morning wood helps you prevent a range of comorbidities, then do it. Identifying and addressing erectile dysfunction in time can help you age gracefully in the long run. Lifestyle can be a powerful tool to avoid and reverse erectile dysfunction. So, eat healthily, maintain a healthy weight, move more, sleep and breathe deep, and cut down on smoking and alcohol.

Did this article help you? Share it with your loved ones. Let us know what else would you like us to write about in the comment section.

Disclaimer: None of what is shared above can replace medical advice. Always make an informed decision. Seek the right professional help. 

If you are struggling with seeking the right help, get in touch with our Sexual Wellness Consultant at You Care Wellness. Book your one-on-one slot here. You can reach out to us on WhatsApp here or write to us at


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