The substance in catnip that makes cats go crazy is called nepetalactone, a chemical compound found in the leaves and stems of the catnip plant (Nepeta cataria). When cats sniff or ingest catnip, nepetalactone binds to receptors in their nasal tissue and stimulates sensory neurons, triggering a response in the brain's emotional and behavioral centers. This activates the cat's opioid system, creating effects similar to natural euphoria, and causes behaviors such as rolling, rubbing, increased vocalization, hyperactivity, head-shaking, drooling, and playful or sometimes aggressive behavior. This "high" typically lasts about 5 to 15 minutes, after which cats become temporarily immune to catnip for 1 to 2 hours. Nepetalactone's biochemical structure is similar to certain feline pheromones, which explains why it elicits these intense reactions in around 80% of cats due to genetic factors. This effect is unique to cats and is not harmful, producing a sense of natural euphoria akin to a mild hallucinogenic experience in humans but specific to feline neurochemistry.