Subjects in the study who had had penetrative intercourse were found to be the least stressed, and their blood pressure returned to normal faster than those who had engaged in other forms of sex such as masturbation.

Those who didn't have any form of sexual activity at all had the highest blood pressure response to stress.

Differences in individual personality and other health-related factors had no effect on the results.

It is thought that the calming effect was linked to the stimulation of a wide variety of nerves, which takes place during penetrative heterosexual intercourse, but not from other forms of sex.

The vagal nerve plays a role in controlling some psychological processes and the release of the hormone oxytocin during sex might have a relaxing effect.

Professor Brody concluded that it made sense in terms of evolution for standard heterosexual sexual intercourse to be associated with a wide range of benefits.

But Dr Peter Bull, a social and political psychologist at the University of York, said there were better ways to prepare for a speech that were more likely to reduce stress including thinking about what you are going to say and preparing your speech properly.