“When you’re cold, your blood vessels constrict, which limits blood flow to your penis,” says Darius Paduch, the director of sexual health and medicine at Weill Cornell Medicine. “This causes it to decrease in size.”
Seems like a cruel biological joke, but there’s actually an evolutionary benefit to shrinkage.
Your body is programmed to preserve heat and energy. So in the cold, it funnels its resources into maintaining blood flow to the middle of your body, where your vital organs are.
But in order to do that, your body has to reduce blood flow to your appendages—your fingers, toes, and your penis.
Meanwhile, your testicles retract and rise closer to the rest of your body so they can also stay warm, says Dr. Paduch.
We all laugh about shrinkage—thanks in part to the classic Seinfeld episode that popularized the term—but for some guys, it can actually be a really uncomfortable experience.
That’s because when blood flow decreases, your penis becomes rubbery. When it jostles around in your underwear or pants, it can cause a pesky, even painful friction, Dr. Paduch says.
The solution: Sport boxer briefs to keep your penis contained and reduce friction, he says.
If a new pair won’t do the trick, your doctor may prescribe an erectile dysfunction (ED) drug like Cialis to help relax the smooth muscles and increase blood flow in your penis.
Don’t worry—this won’t trigger a sudden boner. ED drugs require you to be aroused in order to give you an erection.
Fortunately, shrinkage doesn’t last long. Once you enter a warmer temperature, your body will heat back up, your blood will flow freely again, and your penis will return to its normal size in minutes.
Source: Men’s Health