Why a body can look as if its hair and nails have grown
Hair and nails are made mostly of keratin, a tough protein. The visible strands and nail plates are already dead tissue; they extend only because living cells beneath the skin make new material and push it outward. Hair grows from a follicle, while nails are produced by a growth area at the base of each nail, called the nail matrix.
After death, circulation stops, so those living growth areas no longer receive the oxygen and nutrients needed to keep producing hair or nail. The visible keratin does not keep growing on its own.
The skin changes; the keratin does not
The apparent change comes from the surrounding skin. As a body loses moisture, the skin can dry and shrink back slightly. That exposes more of the hair shaft or nail plate, making the remaining material seem longer. The same effect can make stubble look more pronounced.
It is a change in what is visible, not new growth. A nail that appears to extend has not been pushed forward by a working nail matrix; rather, the skin around it has receded.
A small visual illusion with a simple cause
While someone is alive, hair and nails can grow because their roots contain active cells. Once those cells stop functioning, the process ends, even though the keratin they made remains. The body’s changing surface can reveal more of that keratin, creating the impression of growth without producing any.
