If you’re a male, you are more than likely wondering the same question.

The common answer is that it’s a pee boner. “It’s not directly related to that“, according to Joseph Alukal, M.D., assistant professor of Urology and Obstetrics and Gynecology at NYU Langone Medical Center. “The penis is a very strange organ in terms of its job and the way it traps blood inside it,” says Dr. Alukal.

What is it?

Morning erections, or nocturnal penile tumescence (NPT) as they are scientifically called, are spontaneous erections that occur during sleep or while waking up. All males without erectile dysfunction will experience this and they normally occur around three to five times during sleep.

Why is this happening?

While there are a few different theories over the years to explain NPT, what causes these morning glories still remains uncertain.

One theory is the release of noradrenaline. This is a hormone that the brain releases during the day which hinders erections. When you go to sleep, your brain tends to release less of it, thus making it more likely for your ‘guy’ to pop-up.

As mentioned before, NPT actually happens three to five times during your sleep, so waking up with one or not is really just up to chance.

Related Story: Can scientists erase painful memories?

Is it normal?

One idea is that these sleep exercises actually contribute to the health of your junk. If you are consistently having erections while you’re asleep it is a sign that there is healthy blood flow going to your penis, which is necessary for getting hard when you are turned on.

If you are having a difficult time getting hard when you’re “getting it on”, but it does pop up during your sleep, then erectile dysfunction is not your issue. In this case, you are likely suffering from depression or performance anxiety.

If you can’t get it up in both scenarios, this is a sign that blood flow to your penis is an issue. This might be a sign to see a doctor.