Can Hair Turn White Overnight?
March 3, 2014
For centuries, it has been widely believed that fright can turn hair white. They say that the hair of condemned prisoners (such as Thomas More and Marie Antoinette) turned white the night before their executions. They say that many people who have terrifying experiences with ghosts find that their hair has turned white as... snow. Once can hardly crack a book of ghost stories or "true" ghost encounters without finding this trope!
The idea that psychological trauma leaves a physical mark is an ancient one. Hair turning white, especially from fright or an encounter with a ghost, is a staple in much folklore. It is in fact a well-known traditional international folk narrative motif (F1041.7 in the Motif-Index of Folk-Literature: A Classification of Narrative Elements in Folktales, Ballads, Myths, Fables, Mediaeval Romances, Exempla, Fabliaux, Jest-Books, and Local Legends). It is also featured prominently in many urban legends, describing the results of, for example, encounters with hook-handed serial killers freshly escaped from local insane asylums.
The idea is superficially believable, yet clearly rooted in myth and folklore. Is it true? The story has less credibility than Uri Geller's press agent. It is medically impossible; there is no mechanism by which hair could organically and spontaneously turn white, either suddenly or overnight. Despite cosmetics companies' claims that their products can restore life and body to hair, hair is dead. The main shaft of the hair follicle is extruded, expired biomass no longer influenced by any psychological or physiological processes in the body.
Even if an illness, fright, or sudden shock could in fact turn hair white, it would be weeks before the effect would be visible because only the root would be affected. The same principle is involved when fingernail is injured near the cuticle and the damaged part gradually grows out. It's no more possible for the whole hair shaft to spontaneously turn white than it is for a dead tree branch to sprout leaves.
This leads us to another interesting aspect of the transition from colored to gray to white hair. According to some experts, there is no such thing as gray hair; gray hairs don't exist. Hair can appear gray because individual white or colorless hairs are mixing with hairs that still have color. This is especially visible in "peppered" beards; the gray is a pointillistic illusion. Gray hair might appear to turn white if the colored hair shafts selectively died for some reason, leaving the white hairs behind. It seems that a small bottle of hair coloring can do something that neither impending execution nor ghosts can do.