Why do men wake up with erections? It’s a question all men (and lots of women) must have asked themselves. This video sets out to explain nocturnal penile tumescence from a scientific perspective.

The first thing to note is it’s perfectly normal, so don’t let anyone tell you it’s wrong. It turns out it’s part of your sleep cycle. So if dreaming is considered OK, so should night-time erections.

I won’t go into detail, but the video explains all. The mechanics of what happens is fairly simple, and the reason why men often wake up with an erection is easily explained.

This is a subject matter often avoided for fear of embarrassment, so it’s great to see it explored in a YouTube video.