India, Aug. 30 -- In today's episode of Everyday Explained, we're looking at something you've probably noticed after spending too long in the bath, swimming pool or shower: your fingers suddenly look like tiny prunes. But why does this happen? And is your skin actually absorbing water and swelling up? The answer is more surprising than you might think. (Also read: Everyday explained: Why are school buses always painted yellow? )

For years, the common explanation was that the outer layer of the skin absorbs water and swells, causing it to wrinkle. But research has shown that water-induced finger wrinkling is actually an active process controlled by the autonomic nervous system.

A study published in Muscle & Nerve found that the wrinkling...