Sex can cause spikes in your heart rate, blood pressure, nervous system activity...and, for one poor soul, temporary blindness. Yes, that old wives' tale about sexual gratification making people go blind has, at long last, been proven true...sort of.
The ever awesome NCBI ROFL has the scoop on this strange case history:
Our patient experienced transient monocular visual loss every time he reached the climax of sexual intercourse, but never while performing strenuous physical exercise.
We don't know why it was just sex that was causing the blindness, but the researchers figured out it was vasoconstriction, which is where the muscle walls contract around a blood vessel, restricting the flow of blood:
"Hypothetical mechanisms of transient monocular visual loss in our patient include vasoconstriction or embolism in the arterial blood supply of the eye. The repeated and completely transient nature of our patient's symptoms supports the fact that embolism was not involved, whereas the resolution of the symptoms after initiation of the treatment with the vasodilator enalapril supports vasoconstriction as the cause of transient blindness."
Interestingly, vasoconstriction is the very same condition that causes erectile dysfunction, in which not enough blood can reach the penis to sustain an erection. All right, I think I've lobbed about a dozen different softball set-ups to all the filthy-minded comedians out there, so have at it.