Early Risers: Why Men Get Morning Erections

When guys wake up in the morning, a certain body part also tends to rise. Medically, this phenomenon is known as nocturnal penile tumescence. But it may be better known by the name “morning wood.”

So, why does an alarm clock going off seem to trigger an erection? (Getting up and out of bed really isn’t that alluring after all.)

We asked urologists Ryan Berglund, MD, and Raevti Bole, MD, to explain.

What is ‘morning wood’?

“Morning wood” is the descriptive name given to an erect penis that stands tall in the moments after boys and men awaken after a night of sleep. The moniker, however, is only partly accurate.

“A penis may become erect and then flaccid several times in the course of a night,” says Dr. Berglund. “It’s not just in the morning. You’re simply more likely to notice it happening when you wake up.”

What causes morning erections?

Your body doesn’t completely shut down while you sleep. Essential operations — like your heartbeat and breathing — continue under management from your parasympathetic nervous system (PSNS).

Know what else your PSNS controls? Sexual arousal, including erections in men.

PSNS activity while you catch ZZZs may generate genital activity, particularly during the dreamy stage of REM sleep, notes Dr. Berglund and Dr. Bole. An erotic dream can result in an erection and maybe even ejaculation (or what’s known as a “wet dream”).

Other potential causes of overnight or morning erections include:

• Unintentional stimulation: Tossing and turning in bed may rub you the right way down there and lead to an erection.
• A full bladder: Your bladder is located near your sacral nerve, which sends messages to the brain to start an erection. A bladder filled with overnight urine production can press against the sacral nerve to prompt an erection.
• Hormones: Levels of testosterone, which play a role in erectile function, tend to rise as you sleep. Hitting a hormonal peak after a night of rest can spring an erection.

It should be noted that girls and women can experience a similar form of genital stimulation as they sleep. It’s known as nocturnal clitoral tumescence, or “morning bean,” and can lead to swelling of the clitoris and vaginal lubrication.

At what age do morning erections begin?

A morning erection can occur at any age. Even male fetuses have erections in utero!

“It’s very common for friends of mine who are parents to call and ask if it’s a problem that their 3-year-old has an erection,” shares Dr. Berglund. “The answer I always give them is that it’s totally normal.”

But the regularity and stiffness of morning erections may decrease with age.

Is it unhealthy not to get morning wood?

Waking up without morning wood on occasion isn’t a reason to be overly concerned. But if there never seems to be any lumber down low, it could be a sign of a health issue that deserves attention.

“Nighttime and morning erections are linked to sexual health,” says Dr. Bole. “If they’re really not happening, it could be an early indicator of erectile dysfunction or dysregulated hormones.”

The lack of regular morning erections may also be a sign of sleep disorders or stress.

Talk to your healthcare provider if you notice that you’re rarely experiencing morning erections.

“Err on the side of mentioning it, especially if you’re noticing a trend,” advises Dr. Bole. “They might run tests and find you’re healthy as a horse. But there’s also a chance that they could uncover something that needs attention. There’s a good risk-benefit in checking it out.”