The health problem lurking in your fingers: "If they don't wrinkle even after soaking for hours..."

The perfect shower, one that leaves us clean without damaging our skin, should last about 5 minutes , although in Spain it's common to take a little longer. This is precisely the time it takes for hands and feet to begin wrinkling , something that is even more noticeable when we take a long soak at the beach or pool.

For a long time, it was thought that this happened because the skin absorbed water, causing the epidermis to stretch unevenly. However, it is now known that this is not the case ; it is an automatic response of the body that can be used in some cases to detect a specific health problem.

Why fingers wrinkle when soaked

This is something we can appreciate from childhood ; in fact, it's often the excuse parents use to convince little ones they've spent enough time soaking . Their toes have wrinkled, which means it's a good time to get out of the pool and dry off a bit.

In reality, as parents well know, this isn't a warning that we've been in the water for too long, nor does it occur because the skin on our hands has absorbed the liquid we're in. It's an evolutionary response our bodies have developed as a form of survival , as pharmacist Álvaro Fernández explains on social media.

"When your fingers wrinkle in water, it's not because your skin 'drinks' water like a sponge," the professional confirms, dispelling this outdated theory. "In reality, it's your sympathetic nervous system that, without you realizing it, causes vasoconstriction in your fingers . That is, the blood vessels close, the skin 'shrinks,' and that's why wrinkles appear."

These wrinkles have a reason to appear, "It is believed that it is a phenomenon that occurs to improve grip on wet or slippery surfaces . Just like the soles of shoes, which have patterns to drain water, grip better and prevent you from falling, our wrinkled fingers work better on wet surfaces." The fact that our fingers wrinkle after spending a little time soaking is a sign of a good functioning of the nervous system, "In fact, if someone has damaged these nerves, their fingers do not wrinkle even if they are soaked for hours... that is why it is sometimes used as a medical test."

In fact, this was key to understanding that these wrinkles were caused by a response of the nervous system, when it was found that patients with median nerve injuries did not have this response ; their fingers did not wrinkle, or wrinkled very slightly. During the 1970s, this method was used to evaluate damage to the sympathetic nervous system.

The sympathetic nervous system and its functions

The sympathetic nervous system is responsible for rapid, automatic responses to stressful or dangerous situations, and together with the parasympathetic nervous system, it keeps the body in balance.

This system is responsible for regulating heart rate and respiratory rate , increasing it when necessary to deliver more oxygen and nutrients to the muscles. It also raises blood pressure, controls pupil dilation, muscle contraction during physical action, and sweating, which regulates body temperature . It causes blood vessels to constrict and decreases the production of gastric juices.

If your fingers don't wrinkle after spending time in the water, it could be due to damage to the sympathetic nervous system. This can also be seen in patients with nervous system disorders such as Alzheimer's, dementia, or Parkinson's.

References

National Library of Medicine. (n.d.-b). Autonomic Nervous System Disorders . https://medlineplus.gov/spanish/autonomicnervoussystemdisorders.html

Coon, E. (2023, July 13). Overview of the Autonomic Nervous System . MSD Manual Professional Version. https://www.msdmanuals.com/es/professional/neurological-disorders/autonomic-nervous-system/generalidades-sobre-el-sistema-nervooso-autonomo