Of course, not every cat is susceptible to the euphoric effects of catnip: about 20 percent of cats aren't genetically programmed to respond. Experts say that catnip reactions are inherited and if a cat loves her 'nip, it's likely that mom or dad enjoyed it as well. In general, catnip is an aphrodisiac and it seems to affect males more than females. Kittens younger than six months old who haven't developed sexually usually avoid catnip.

If you think watching your ten-pound housecat enjoying the effect of catnip is amusing, imagine watching a five-hundred-pound lion roll around like a kitten. Most big cats -- including lions, cougars, bobcats, lynx and leopards -- react to catnip with the same cheek-rubbing antics as your favorite domestic cat. Tigers, however, seem to be immune to the herb's effects.

So what is it about catnip that's makes most cats large and small purr? The "high" appears to be triggered by the plant's release (in oil form) of the chemical nepetalactone, which is similar to the sedative ingredient in the herb valerian, which has been called the "Valium of the nineteenth century." (The two substances are not related.) Humans, of course, don't generally turn cartwheels in the air or bounce around on the furniture after taking valerian: they skip straight to the gentle sleep portion of the effect.

As with sleeping or pain medications or almost any kind of drug that humans use, prolonged use of catnip establishes some immunity. If catnip is too readily available, your cat is liable to get bored and lose interest.

The best way to keep your cat interested in her catnip toys is to store them in the freezer (to help them keep their freshness and to keep your cat from finding them) and bring them out once every two to three weeks for a special catnip party. As an added bonus, during catnip parties you can turn off the TV and let yourself be entertained by your cat's antics.

If you have more than one cat, make sure that you have enough catnip toys to go around; cats tend to be very possessive of their 'nip and will try to hide their catnip toys. Cats can also get aggressive when given catnip, and you don't want your fun-filled party to turn into a cat fight.

While your cats are enjoying chasing their catnip toys, why don't you pull out the teapot and brew up a pot of catnip tea. Although catnip doesn't give humans the same euphoria as it does cats, it has been used for centuries to ease stomachaches and headaches, relieve colds and fevers, sooth colicky children and ease menstrual cramps. A cup of catnip tea can sooth anxiety, provide a restful night's sleep and help hyperactive kids settle down. Some companies sell catnip tea, but to create your own, simply cut up leaves and brew them as you would other types of loose tea. Catnip can also add an unusual flavor to sauces, soups and stews.

Catnip toys and loose catnip are both available, but catnip toys are often the best choice because the catnip is contained and you won't end up with loose leaves all over your house. It's the scent of the catnip and not the taste that creates the euphoric effect, so your cat won't be deprived if you choose toys over loose catnip. Catnip toys for your feline friends come in all shapes and sizes -- from the traditional mice to holiday favorites such as Santa figures and pumpkins.

If you're looking for loose catnip to cook with, you can either purchase it or grow your own. Catnip is a perennial herb with white or pale lavender flowers that can grow up to five feet tall; it prefers full sun and well-drained soil. You can harvest and dry the catnip leaves as needed. Plus, catnip contains citronella and can act as a natural insect repellant. The only caution about growing catnip is that once the leaves are bruised and release their scent, cats will come running to play in your catnip garden.

Catnip's potency, like that of other herbs, is affected by a number of factors, including soil, growing conditions and climate. Cats can have different reactions to catnip grown under different conditions, so if your cat isn't responding to the catnip in her fuzzy mouse, try buying a new catnip toy and see if there's a different reaction.

Another factor that can affect your cat's reaction to catnip is the herb's age. Although it doesn't take much catnip for cats to go bonkers -- they respond to catnip in concentrations approaching 1 part per billion-- it's important to remember that catnip loses its potency over time because the nepetalactone that causes the euphoric reaction breaks down. Storing catnip in the freezer can prolong its life and keep it safely out of your cat's reach for those special occasions when you and your cat can both enjoy it.

And that only leaves one question . . . what is it that cats dream about when they're on a catnip trip? Perhaps it's that ideal world of cat kind -- a world where birds fly low, dogs run slow and people walk around with their pockets full of catnip.