If it is difficult to have or maintain an erection while awake, but not during sleep, this can point to an underlying psychological cause, rather than a physical one. Whatever the reason behind nocturnal erections, they can be useful as a diagnostic tool. So, by reducing the inhibition, the penis becomes erect.

These cells inhibit the tone of the penis. However, because people with vaginas experience something similar - nocturnal clitoral tumescence - bed wetting prevention is probably not the entire answer.Īnother potential explanation is that REM sleep is linked with switching off cells that produce noradrenaline in the locus coeruleus, which is in the brainstem. One theory is that it might help prevent bed wetting: An erection inhibits urination.Ī full bladder is known to stimulate nerves in a similar region to those involved in erections. This is also called “nocturnal penile tumescence,” and it’s still not clear why it happens. Most people with penises have 3–5 erections every night, mostly during REM sleep.