A nice, relaxing bath could result in wrinkly fingers and toes. But what causes this to happen? iStockphoto.com /Yanik Chauvin

After finishing up a long, relaxing bath or a refreshing swim in the pool, you probably notice that the palms of your hands and the bottoms of your feet have become wrinkled as a prune. Although the swelling and wrinkles should go away, you might have wondered why your skin reacts like this after time spent in the water.

The skin's outermost layer, the epidermis, is responsible for this wrinkly reaction, which usually occurs after you've spent about half an hour in the water. The epidermis contains the protein keratin, which strengthens your skin and helps keep it moist. Dead keratin cells make up the epidermis' own surface layer known as the stratum corneum, which is Latin for "horned layer" [source: Meyer].



These dead keratin cells in the stratum corneum absorb water easily and start to swell after extended periods in the water, but the living keratin cells deeper in the skin do not. As the dead cell layer expands, it begins to take up more surface area, but it's still connected to the living cells beneath and doesn't have anywhere to go. As a result, the stratum corneum wrinkles to give the temporary new surface area someplace to go [source: Library of Congress]. Researchers are studying other theories for what might help cause the wrinkling, such as the whether the constriction of blood vessels is related to it.

But if most of your body is submerged in the water, why do these wrinkles occur only on the hands and feet and not on other areas? Because they get so much use, the palms of your hands and the soles of your feet have thicker skin -- and therefore a thicker layer of keratin -- than the rest of your body [source: Meyer]. This makes them especially susceptible to wrinkling in water.

Unlike wrinkles you get when you're older -- which are usually the result of sun damage, dry skin or loss of fatty tissue -- those caused by water absorption are temporary and should go away soon after you dry off. For more information on the skin and wrinkles, visit the links on the next page.