I'm posting a link to a site that goes into detail about the limbic system, essential oils and stimulating the neurotransmitters. I could attempt to sum this all up but I'll destroy it and confuse you.
>Table of Contents half way down
>5.4 Essential Oils For Tics
***Seek the advice of a medical professional before trying Lavender or any natural treatments.
***I AM NOT a medical professional and do not recommend anything beyond research.