Hi I'm Craig, insert joke here, and this is Mental_Floss on YouTube. Today I'm gonna answer StarlingUK's big question "I have arthritis, why do my joints hurt more when it rains?"

Many people with arthritis have noticed joint pain during weather changes, experts still aren't positive that this is a consistent or even real phenomenon, but there's some research about it and I'm gonna talk about it to you today, because that's what I do, I talk at you about stuff. Let's get started.

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In a study published in the journal PAIN, a psychologist surveyed people with chronic pain in four different US cities: San Diego, Nashville, Boston, and Worcester Massachusetts. He found that 2/3 of patients complained the weather had an impact on their pain. They also reported feeling those impacts before the weather itself changed. Other studies have concluded that people with joint pain are affected by any severe weather change, including rain. I'm only happy when it rains. (sings) I'm only happy when it's complicated. No but seriously.

It's worth noting that changes in weather don't change the severity of arthritis, it just temporarily affects the symptoms. Still, some experts aren't convinced that the weather is connected to chronic pain or joint pain. Many claim that this phenomenon has been studied for a very long time but no researcher has ever observed a true objective relationship between joint pain and extreme weather.

For instance, a study conducted in the mid 90's examined 18 people who had rheumatoid arthritis and could find a connection between the two. The professor who designed the study believed that the phenomenon was all psychological, and it's still the case that most of the claims about joint pain and weather are anecdotal evidence, like the study in the four cities.

Yet other experts insist that there's science that proves the relationship between the two. They just don't give up, they got moxie. Chutzpah. Pluck. The prevailing theory about this now is that barometric pressure causes the pain. Barometric pressure is the weight of the atmosphere at a given moment.

Everyone's joints have baro-receptors which are sensitive to changes in barometric pressure. When that happens, the fluid in the tissue might expand, and that swelling causes the already sensitive joint to rub against muscles and nerves, and that will make a person feel more achy than usual. Arthritis is a disease that affects every part of the joint, including the joint lining and some ligaments. These parts of the body have a lot of nerve endings, so it makes sense that they'd be sensitive to swelling, too.

Experts who believe this also point out that it happens to everyone, but people without arthritis aren't as sensitive to it because they tend to have more cartilage protecting them.

Thanks for watching Mental_Floss on YouTube, which is made with the help of all of these nice cartilages. If you have a big question of your own that you'd like answered, leave it below in the comments. See you next week, rain or shine.