Have you wondered why some cats exhibit strange behavior when exposed to catnip? They act much like a female cat in heat: They may rub their head and body on the herb or jump, roll around, vocalize and salivate. This response lasts for about 10 minutes, after which the cat becomes refractory to catnip's effects for roughly 30 minutes. Response to catnip is hereditary; about 70 percent of cats exhibit this behavior in the plant's presence, although it does not affect kittens until they are about six months old and begin to reach sexual maturity.