In the age of Wikipedia, this is clearly no longer true.
During pon farr (mating cycle), the brain is thrown into a neurochemical imbalance and loss of logic and emotional control. The individual may stop eating and sleeping. As the condition progresses, the Vulcan undergoes the plak tow, or blood fever, and becomes unable to speak or think clearly - thoughts of mating overwhelm them.(Link. Also see Kolinahr)