The sexual activity is a biological process involving
stimulation of pleasure centers, and pleasure in itself counteracts, anxiety.
If we want to explain this more deeply we can say that erection by itself
involves parasympathetic and dopaminergic stimulation and these mechanisms as -
it is well known-work positively on the rewarding center in the limbic system
so that the person feels relaxed and happy after sexual activity particularly intercourse.

Anxiety, on the other hand, if exists prevents sexual
activity from being fulfilled, so this area of interest is very complicated and
it is not well understood due to the fact that a lot of neurotransmitters and
centers in the brain and in the spinal cord which are involved and should make
delegate balance among each other so that the process will be accomplished
successfully.