Why Do Men Get Morning Wood?

An erection is a response to a combination of factors involving the nervous system and the endocrine system. 

When sexually aroused, the brain sends chemical messages to the nerve endings in the penis. This in turn causes blood to flow into the penis. Muscles in the penis then contract to trap the blood, which results in an erection.

Morning wood is most likely caused by a number of factors. But here are two theories:

1. Physical stimulation from a partner (which could be accidental) may cause an erection, even if your eyes are closed.

2. Hormones may also play a part. Testosterone levels are at their highest in the body immediately after waking from the REM stage of sleep. This may be enough to cause an erection, despite there being no visual or physical stimulation. 

One argument that supports this is that natural levels of testosterone begin to drop in men aged 40-50 years. At the same age, the incidence of nocturnal penile tumescence starts to decrease.

It’s not clearly understood what causes a man to have erections during sleep. However, erections occur during the rapid eye movement (REM) stage of sleep. So it’s thought that increased activity of the parasympathetic system during REM sleep may be involved.

Typically, the last period of REM happens before you wake up, which might be why men will often wake up with an erection.

There’s also a theory that the body releases hormones to suppress erections when men are awake. The brain ‘relaxes’ at night and releases less of those suppressive hormones, which allows the erections to occur.

Some also think nighttime erections have a function: to keep the erectile tissue in good shape and make sure your erectile function stays healthy.

They may also indicate that the bladder is full. The fact that an erection will subside as soon as you empty your bladder strengthens this argument.

Despite these theories, the only thing that we are sure of is that nighttime erections happen when erectile function is healthy.

Morning and nighttime erections are a normal part of male life and a frequent occurrence for adult men.

Although male babies can have erections, morning erections tend to occur with increasing size, rigidity and frequency as puberty progresses.

The absence of morning erections can be a sign of ED. Although it’s important to take into account that frequency of morning erections decreases as men get older. 

And ED can be an early indicator of an underlying disease such as cardiovascular disease or diabetes. So a lack of ‘dawn horns’ may suggest that it’s time to visit the doctor for a check-up.

Other causes of ED include:

• Heart disease
• Atherosclerosis
• High blood pressure (hypertension)
• High levels of cholesterol
• Obesity
• Lack of regular exercise
• Parkinson’s disease
• Multiple sclerosis
• Peyronie’s disease
• Smoking
• Alcohol abuse
• Sleep disorders
• Some prescription medication as well as some illegal drugs

• Although some people may find them a nuisance (especially if they sleep on their front) morning erections are a good indicator of normal, healthy blood supply to the genital area.

• If you find that you are getting fewer morning erections – or no morning erections at all – it is probably time to discuss things with your healthcare professional. They can check for more life-threatening conditions such as diabetes and give you advice on lifestyle issues. 

• Fortunately, there are many treatments available for both underlying conditions and ED. So help is out there if you need it.

Editor’s note: This article was originally published on December 8, 2020. It has been updated for accuracy, readability and comprehensiveness.