Scientist explains the three key reasons why 'morning glory' happens

'Morning glory' (yes, you know exactly what that is) happens pretty often and it can usually happen around three-to-five times during an eight hour sleep (something you may not be aware of).

It's actually called nocturnal penile tumescence but 'morning glory' is a much better name for it, isn't it?

And it turns out for those of us with a penis who do wake up at full mast, it can be a good sign that everything is healthy down there and not necessarily anything to do with a naughty dream.

Sergio Diez Alvarez, director of medicine at The Maitland and Kurri Kurri Hospital and the University of Newcastle, has said there are three key reasons why this is the case.

A scientist has revealed three key reasons why 'morning glory' happens / gorodenkoff, iStock

In a post on The Conversation in 2016, Alvarez said: "Nocturnal penile erections occur during Rapid Eye Movement (REM) sleep (when we dream). They occur when certain areas of the brain are activated.

"During REM sleep, there is a shift in the dominant system that's activated. We move from sympathetic (fight and flight) stimulation to parasympathetic (rest and digest) stimulation."

It's this shift that effectively causes it to happen.

"Testosterone, which is at its highest level in the morning, has also been shown to enhance the frequency of nocturnal erections," Alvarez said.

"Interestingly, testosterone has not been found to greatly impact visual erotic stimuli or fantasy-induced erections. These are predominantly driven by the 'reward system' of the brain which secretes dopamine."

And some believe it can happen when your body is telling you to go to the loo.

"It’s more likely the reason for the morning erection is that the unconscious sensation of the full bladder stimulates nerves that go to the spine and these respond directly by generating an erection (a spinal reflex)," Alvarez concluded.

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