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Why is cracking my knuckles so addictive?

We ask a lot of weird questions here at The Body Odd. But so do you! Here's our answer to one of your latest queries. Got an inquiring mind? Head over to our Facebook page and ask us your oddest health, medical or human behavior question. We may answer it in an upcoming post.

Today's question: Why is cracking my knuckles so addictive?

The pop! pop! pop! of each cracked knuckle is so sweetly satisfying to you. But it's slowly driving everyone around you completely nuts. You don't remember when you started it, but you can't seem to make yourself stop. Why? "There’s not any hard science to explain why it’s so addictive, but certainly people speculate it’s one of these activities that releases nervous energy," says Dr. Rachel Vreeman, assistant professor of pediatrics at Indiana University School of Medicine and co-author of "Don't Cross Your Eyes ... They'll Get Stuck That Way!"

Some people twirl their hair, some people jiggle their foot up and down -- and some people pop their knuckles. "Many people who do it believe that it feels good," Vreeman says. "They find it to feel good or comfortable, or it even gives them some physical release."

We should note that when you "crack" your knuckles -- you're not actually cracking anything. "That sound you hear is synovial fluid vapor cavities -- or gas bubbles -- in the fluid around your joints. With certain amounts of pressure you can make those bubbles burst." She's making it sound like popping bubble wrap -- no wonder both activities are equally satisfying. 

And, no, cracking your knuckles won't give you arthritis, despite wild rumors you may read on the Internet. Vreeman says in studies of hand function in adults both with and without arthritis, those with arthritis weren't any likelier to be knuckle-crackers. In other words, she says "It doesn’t seem like you’re likely to get arthritis because of your annoying knuckle cracking."

Still, habitual knuckle-popping might lead to some hand discomfort, including swelling, reduced hand strength and even some finger or joint injuries. So, how do you knock it off? 

"Certain things that make you more likely to break your bad habit: coming up with a clear plan. Having some accountability. Telling other people about it," Vreeman says. "From weight loss literature we find that people do better with modifying their eating habits by keeping records -- so keep some record throughout the day how many times a day you did it.

"We also know from sort of the science of habits that it takes ... 28 days to form a habit," Vreeman explains, "so to form an opposite habit probably takes at least that long."

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