Why Do I Shiver When I Pee?

Regular Floss readers know that scientists around the world study some pretty silly things. A few weeks ago, I wanted to know why spaghetti doesn't break in half. A simple Google search gave me an in-depth study of the phenomena by two physicists and plenty of charts, equations and even videos of their experiments. In our annual 10 Issue, Chris Weber wrote about the most recent batch of Ig Nobel Prize winners, who have put plenty of time and effort into things like extracting vanilla flavoring from cow dung.

Surely, on the next line, I'll present you with the results of a much-lauded study that conquered the mystery of the post-micturition convulsion syndrome (or, the "pee shivers"). But guess what?

No one has ever studied it.

Science has given us vanilla made from feces. It's discovered that Viagra aids jetlag recovery in hamsters. It's detailed the injuries that a falling coconut can cause. But for some reason, no one wants to touch the pee shivers. And so, we're left with...

THE THEORIES

The most plausible one, espoused by a number of scientists who aren't this guy, is that the shiver is a result of two parts of the autonomic nervous system (ANS) getting their streams crossed. The ANS is a control system for involuntary muscles affects things like heart and respiration rates, digestion, body temperature control and urination.

The ANS has two divisions. The sympathetic nervous system (SNS) controls bladder function, among other things. It keeps the bladder relaxed and the urethral sphincter contracted so you don't have to concentrate on not peeing your pants all day. The parasympathetic nervous system (PNS) relaxes the urethral sphincter and contracts the bladder when you decide to answer nature's call.

Part of the SNS response to a full bladder is the release of chemicals like catecholamines (which include epinephrine, norepinephrine and dopamine). When you finally grab a minute to urinate, the PNS takes over, and catecholamine production changes. Some sources point at the change in chemical production as the cause of the shiver, and others say it's the SNS to PNS switch itself that does it.

As I said, this is just a theory (and there a plenty more out there, too, like the shiver being caused by exposing your naughty bits to the colder temperature outside your pants), and no one has conducted any laboratory research to confirm it. If you've got some time on your hands this summer, maybe we can hook you up with a mental_floss grant to study this more thoroughly.

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