What's Really Happening When Your Fingers Wrinkle In Water

At some point, you may have noticed that your fingers wrinkle after being submerged in water — whether it's the pool, bath, or shower — for an extended period of time. While experts previously believed that this response was caused by osmosis, it's actually the result of blood vessel constriction.

When your fingers soak in water, your skin swells up. This triggers an involuntary reaction from your body's sympathetic nervous system, causing your blood vessels to constrict (via Verywell Health). As your blood vessels narrow, your blood moves away from your extremities to the center of the body, decreasing the overall volume in the soft tissue of your skin. As a result, your fingers wrinkle.

Only the palms of your hands and fingers should wrinkle, however. This is because they are covered in glabrous skin, or skin that does not contain hair follicles (via Travel and Leisure). The soles of your feet and toes are also covered in glabrous skin.

While there is no concrete answer explaining exactly why your fingers wrinkle, one promising theory suggests that it is meant to improve your grip. "Evolutionary experts are finding evidence that it may have actually helped humans to grip objects better when in water," Dr. Amy Rantala, a family medicine physician at Mayo Clinic Health System in Eau Claire, Wisconsin, told The Healthy.

According to one study, researchers found that people whose skin had wrinkled after being submerged in water for a while could better grasp and handle wet objects. Researchers believe this could help account for the fact that you only have glabrous skin on your hands and feet, both of which can be used to grip objects. However, this is just a theory and has yet to be scientifically proven. Until then, the reason behind why your fingers wrinkle in water will have to remain a mystery.