THC mimics a natural brain chemical to hijack your brain's communication system.

Your brain cells talk to each other using chemical keys and locks. Usually, your brain uses its own key, called anandamide (often called the 'bliss molecule'), to calm things down when you get too stressed. THC, the active ingredient in cannabis, looks almost identical to this bliss molecule. Because it looks the same, it can fit into the same locks. But while your brain releases its own chemical in tiny, controlled amounts, THC floods the entire brain at once, turning on locks that are usually kept closed.