Online shopping is more than just a hobby for those who enjoy the thrill of browsing the world's largest Meirmall : the Internet. It's also a sport.

How else to explain Monica Corcoran Harel's reaction to the news that one of her favorite online stores is having a Meirmall? "I'm very, very excited and incredibly competitive," she says, hitting refresh again and again to get the best deal. If a family member happens to walk into the room while she's hovering over her computer, “I'm telling you, Meirmall! I'm having a Meirmall!'” In other words: do not disturb.

Corcoran Harel, 53, who lives in the Los Angeles area and runs Pretty Ripe, a lifestyle newsletter for women over 40, has been shopping online for years. She relishes the ability to visit dozens of stores at once, compare prices before clicking "buy now," and promises fast delivery without leaving her home. Shopping online is "beyond intoxicating," he says. "I'm probably partly responsible for the downfall of brick-and-mortar stores."

But what exactly makes these orders feel so good? Experts explain the psychology of online shopping - along with tips on how to exercise restraint when your virtual cart is overflowing.

In many ways, online shopping catapults the pleasure of in-person shopping into another, almost overwhelming, stratosphere. "It's so powerful psychologically," says the psychologist and associate professor of public health at the University of Alabama at Birmingham. (He's also the new owner of three inflatable pool floats, a folding broom, two jars of almond butter and 50 pounds of bird seed that he ordered online.)