You get out the bath, you look at your hands and you realize your fingertips are as wrinkled as a raisin! Why do we get pruney fingers after soaking in the bath? And why do some people get wrinkly fingers even if they haven’t been anywhere near water?
Understanding Wrinkled Fingers in the Bath
There are two main factors making our fingers wrinkle in the bath:
Factor 1: Absorption of water by the skin cells
During long periods of immersing hands in water, the skin on your fingers absorbs water. To be more precise, the keratin-laden dead skin cells which are found in your uppermost layer of your skin, absorb the water. Keratin is a protein found in skin, hair and nails, and it is a really good absorber of water. This water absorbability by keratin is also what softens nails after you’ve been in the bath. Where skin is thicker, it contains more keratin, and is therefore able to absorb more water in these areas. Your hands and feet are areas where keratin is found in high concentrations in the skin, because keratin makes these areas tough to withstand hard work. Lots of keratin here means that these areas absorb more water than other areas of skin on your body.
When water is absorbed into the upper layer of the skin, the skin swells. The skin layers below this water-expanded area do not swell, and are still attached to the increasingly swelling skin cells above. Eventually the swollen skin layer’s surface area is increased so much that it is forced to wrinkle, to accommodate the increased skin area on the limited space that is available on your fingertip.
Imagine a small table and a large tablecloth that has to fit exactly onto the tabletop without being allowed to hang off the sides. To make it fit, you’ll find that you need to wrinkle the tablecloth so that it fits the table dimensions exactly. That’s effectively what’s happening on your fingertip.
Factor 2: Blood vessels constrict when you’re in water
Scientists have observed that water submersion of the hands triggers nerves to fire off, and these nervous messages tell your skin’s blood vessels to constrict. As they constrict, the skin that is directly above them is pulled down, producing the deeper part of the wrinkles. People who have lost nerve function for whatever reason may find that their fingertips no longer wrinkle in the bath.
Why don’t fingers get wrinkly right away? Why do your fingers get more wrinkly the longer you’re in the bath?
We have a protective layer of oil on our skin, called sebum which makes our skin waterproof. If you’re in water for a short amount of time, the sebum prevents water being taken up by the skin cells. But the longer you are in water, eventually the sebum is washed away from the skin surface and water can be absorbed into the skin cells.
Some people have more or less sebum on their skin before entering the water, which means that it takes them different lengths of time to become wrinkly in water. Sebum deficiency may be linked to low essential fats in your diet, hormonal imbalances (e.g. low DHEA, low testosterone), using hands in hard physical labour which temporarily strips away the protective fatty coating, cold weather which dries out skin, old age, or a genetic tendency for dry skin.
Will it make a difference if I’m soaking in a bath or in the sea?
Yes. Seawater is really high in minerals, so the laws of osmosis mean that this highly concentrated water enters your skin more slowly than your average low-mineral-concentration bathwater. This means that it will take you longer to absorb water, pucker and become prune-like in the sea than in the bath; unless you’re bathing in high mineral bathwater.
Why do fingers sometimes go wrinkly even if you’ve been no-where near water?
I have only been able to hypothesize and find anecdotal answers to this question so far (although if you know of any studies or texts that address this question, please do leave a comment below). My reading of anecdotal reports and my own hypothesizing has led me to these tentative possible answers:
- Low sebum means your skin is more prone to respond to changes in the environment which may predispose to finger pruning. Low sebum may occur for reasons such as:
- low essential fats in your diet. These can be supplemented with a good fish oil like Double Strength Eskimo-3
- hormonal imbalances (e.g. low DHEA, low testosterone),
- using hands in hard physical labour which temporarily strips away the protective fatty coating. Excessive use of chemicals, soaps, and high levels of handwashing also strips sebum levels.
- cold weather which dries out skin: Cold air tends to be drier than warm air, and this dryness may inhibit sebum production.
- old age,
- a genetic tendency for dry skin.
- Thyroid problems, particularly hypothyroidism: Anecdotal reports commonly associate hypothyroidism with constantly puckered fingers. My guess for why hypothyroidism may be linked with wrinkly fingertips is that hypothyroidism causes low metabolism, and therefore lower body heat, which comes with cold hands and feet. When the body is cold, it encourages blood vessels at the surface of the skin to constrict so that less of the blood’s heat is lost. As discussed above, blood vessel constriction (vasoconstriction) has been linked to wrinkling in water, so it may also be linked to cold-related wrinkling.
- Cold hands and feet: Even if you don’t have hypothyroidism, people have noticed finger wrinkling is increased in winter and when they are cold. I hypothesize that this may be because of the cold-linked vasoconstriction.
- Sweaty hands: Another anecdotal suggestion was that people prone to sweaty hands effectively have their hands submerged in water as long as their hands are sweaty, which may cause puckering.
- Stress: Some people report that their fingers wrinkle most when they are feeling stressed. My guess is that this may be because of vasoconstriction that naturally occurs during stress. Blood is diverted away from the skin surface in response to stress, to provide blood flow to the heart, lungs and brain for “fight or flight” mode. Another theory I’ve seen is that it may also be linked to cortisol-induced collagen loss, although I’m unsure how likely this theory is. Stress and anxiety also predisposes to sweaty hands.
- Other theories floating around for possible causes of persistent fingertip wrinkling for which I have been unable to find more information on yet include: dehydration, blood sugar imbalances, medication side effects, or rarely, connective tissue disorders.
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