It is a common belief that hair and nails continue to grow on a deceased body, a notion often perpetuated in popular culture. This idea, however, is a widespread misconception. Scientific understanding clarifies that actual growth of hair and nails ceases at the moment of death. While the appearance of growth can be unsettling, it is an illusion caused by changes in the body after life functions have stopped.
Why It Seems They Grow
The visual phenomenon that leads to the belief of post-mortem hair and nail growth is primarily due to the dehydration of the body. After death, the skin and other soft tissues begin to dry out and retract. This causes the skin around the hair follicles and nail beds to pull back. As the skin recedes, it exposes more of the hair shaft or nail plate that was previously covered, making them appear longer than they were at the time of death. This creates an optical illusion of continued growth, rather than actual biological activity.
This retraction is particularly noticeable with nails, where the drying of the surrounding flesh makes the nail plate seem more prominent. Similarly, on the scalp, the shrinking of the skin can give the impression that hair has lengthened or that stubble has grown. Embalming can even accelerate this drying process, making the illusion more pronounced.
The Science of Stoppage
The cessation of life functions directly impacts the biological processes necessary for hair and nail growth. Hair originates from follicles in the skin, and nails grow from a specialized area under the cuticle called the nail matrix. Both processes rely on continuous cell division and the production of new cells. This cellular activity requires a steady supply of oxygen, glucose, and other nutrients, all delivered through the circulatory system.
When the heart stops beating, the flow of oxygenated blood ceases, leading to an immediate halt in the supply of these essential resources to cells throughout the body. Without oxygen, cells quickly lose their ability to perform metabolic activities, including the energy-intensive process of cell division. Therefore, the cells in the hair follicles and nail matrix, which generate new keratinocytes, can no longer divide. Hair and nail growth also involve complex hormonal regulation, which cannot be sustained after death. While some cellular activity might persist for a few hours in certain tissues after circulatory arrest, the organized, sustained process of growth requires a living, functioning organism.