Many sexually mature men wake up in the morning with an erection. Some refer to it as a “woody,” others a “stiffy,” many as a “hard-on,” and so many other names as well. There have been scientific and not scientific studies on why men experience erections when they wake in the morning, but nothing has been conclusively proven yet. However, morning erection is perfectly common, normal and natural. What are the causes of morning wood? Should you worry if you don’t have morning erection experience?

What Is Morning Erection?

Morning erections have colloquially been termed as “morning wood” while scientifically it is called nocturnal penile tumescence. It is a normal and healthy physiological reaction and response that most men experience in their lives. Morning erections are really the ending of a series of erections that happen to men during the night. Healthy men can, on average, have anywhere between three to five erections in a full night of sleep, each of which lasts from 25-35 minutes.

What Causes Morning Erection?

When blood rushes into the penis it causes an erection. Usually there is some kind of arousing stimulus, but younger men and boys can experience erections without arousing stimuli present. There are a number of things that happen while you sleep that contribute to an erection upon waking up.

1. Full Bladder

Urine retention during the night causes the bladder to become full. As urine fills the urethra, the penis becomes engorged and will often become erect. There is a theory that states the penis becomes erect in the morning in order to prompt the male to wake up and use the bathroom. Some men may not always be roused instantly when nature calls, but the idea is that they will feel their erect penis as they become more awake and realize that they need to be relieved. The discomfort of a full bladder can awaken anyone from a deep sleep, but imagine a man lying face down with a budding erection in his mattress. This will cause him to wake up for sure and compel him to relieve his bladder.

2. Brain Activities During Rapid Eye Movement (REM) Sleep

Men generally will experience four intervals or stages of REM sleep each night. Erections can occur during REM sleep and thus be carried over into morning. The most vivid, lifelike dreams occur during this stage of sleep which can often cause physical reactions, such as an erection, without the sleeper waking up. Some men, usually sixty or older, can experience erections in non-REM sleep.

Specific neuro-reflexes that are stimulated during REM sleep are the cause of the spontaneous erections that occur, and morning erections are simply the tail end of those. Since REM happens towards the end of the sleep cycle, a man can still be experiencing the physical effects of it when he moves into wakefulness.

3. Use of Erectile Dysfunction Medications

Erectile dysfunction (ED) medications like sildenafil (which is Viagra) and tadalafil (which is Cialis) can impact men and their morning erections. The kinds of medications can cause morning erections if they were taken the previous day or night prior to sexual activity. It has been found that morning erections are more common in men taking drugs, Like Cialis, than in men who do not use these drugs.

Bear in mind there is no reason to take an erectile dysfunction medication simply to give yourself a morning erection. Morning erections are not an indicator of penile function or dysfunction.

Watch the following video for a look at the science behind morning erections:

What If You Don’t Experience Morning Erection?

Early research did not find any conclusive differences in morning erections between older men and those of younger men. More recent research studies have shown a slight gradual decline in the frequency of morning erections in men as they age. Younger men seem to have more frequent morning erections, but the numbers do begin to drop off as they age. Certain studies have found a general decrease in rigidity and length of time of the erection.

When there is a lack of morning erections that are accompanied by a lack of erections overall, it may suggest a physical rather than psychological cause. One cause could be that testosterone levels are too low or fluctuating too much. If you have concerns about noticeable changes in your morning erections and their frequency, consult your doctor or primary care physician to see if there is a more serious underlying issue. Keep in mind, though, there are a variety of cause and factors that lend their influence to morning erections, especially things like the length and quality of your night sleep. Changes in morning erections, such as a decrease or lack of them, do not necessarily mean there is a serious problem.