Have you ever stayed in the bath or swimming pool for a long time and noticed that your fingertips had become wrinkled? The same thing can happen when you wash dishes or soak your hands in water. Although it may look like your skin has simply absorbed too much water, scientists have discovered that the process is more complicated.
The wrinkling usually appears on the fingertips and toes after they have been immersed in water for some time. Researchers have found that it involves the autonomic nervous system, which controls many body functions that happen without conscious effort.
When your fingers remain underwater, the small blood vessels beneath the skin narrow. This process is called vasoconstriction. The change in blood flow affects the tissue beneath the skin and helps create the familiar ridges and grooves on your fingertips.
Scientists are still investigating every detail of why this response happens, but research suggests that it may have a practical benefit. One study found that people handled submerged objects more quickly when their fingers were wrinkled than when they were not. The researchers suggested that the wrinkles might help the fingers grip objects in wet conditions.
However, not every study has found the same benefit. Other researchers reported that wrinkled fingers did not improve performance in their tests. This means the idea that wrinkles evolved specifically to improve grip remains a possible explanation rather than a settled fact.
The change is generally temporary. Once you leave the water and your fingers dry, the wrinkles gradually disappear as the skin and underlying tissues return to their usual state.
Interestingly, water-induced finger wrinkling also depends on healthy nerve function. Researchers have studied this response as one way of examining parts of the nervous system that control automatic functions.
So, the next time your fingertips become wrinkled after a bath, remember that it is not simply a sign of water soaking into your skin. It is a response involving your nerves and blood vessels, and scientists are still learning exactly why it happens.