For centuries, it has been claimed that human hair can turn white 'over night.' Yet, this astonishing claim has so far not been investigated systematically. Still, several authors of the medical setting wrote articles that are commonly thought to have shown that human hair cannot turn white within one or a few days. Typically, authors of such articles devaluate existing reports of sudden whitening, and stress that inanimate organic matter without metabolism cannot change its colour.

The most frequently cited 'review' paper of this kind was written by Josef Jelinek in 1972. Jelinek, however, included only a very small fraction of the existing case reports in his paper and omitted practically all first-hand observations published by physicians in the medical literature. Moreover, the summaries of the few case reports he included in his review contain conspicious errors, and one must wonder how thoroughly Jelinek had read the original publications.
In short, Jelinek's paper is a good example of bad science. It nicely illustrates how a 'science myth' is created on virtually no foundation, and is perpetuated for decades without being questioned.

Consequently, because no authoritative source summarizing the state of the art regarding the sudden whitening of body hair was available, I performed a survey of the German, English, French, Spanish, Italian and Dutch medical literature, roughly covering the last 200 years.

In sum, I found 207 case reports of which 46 were first-hand accounts of physicians who witnessed the rapid graying process of their patient's hair. In addition, 87 cases were reported by physicians who saw or treated the patients only after the alleged sudden color change, sometimes on the next day after its supposed occurrence. The case collection contains 24 cases in which persons aged 4 to 18 were reported to have undergone a rapid graying of hair.

The graying was mainly related to the contexts of emotional trauma or stress, psychiatric disorders, and somatic diseases. Numerous cases involved not only scalp hair, but also beards, eyelashes, and other body hair. Several authors stressed that the loss of hair was not involved in the process of graying.

Since I began to study the subject of sudden whitening of hair, I  received 11 accounts in which people related to me how hair turned gray or white within one or a few days.

In the non-medical literature, I even came across two reports that described how animals have allegedly turned white from fright. One of them concerns a horse that was found three days after it had suffered a tremendous shock and escaped. During these three days, his former black tail and mane had ostensibly turned gray and white, respectively (see the picture on the right).

Taking these case reports together, especially some detailled first-hand accounts related by physicians, I think it is very likely that sudden whitening or graying of developed hair shafts does indeed occur - just like many other astonishing changes of living body tissues that may occur in emotionally charged circumstances or in near-death states, and for which there is, at present, likewise no satisfying physiological explanation.
Perhaps, these phenomena are already linked to so-called Psi-phenomena such as psychokinesis.

In science, the presence or the absence of a given phenomenon determines if it is real, not the presence or the absence of a theory to explain this phenomenon.
Hence, when a theory is lacking, it is the task of science to start investigations into the as yet unexplained.

I hope my research will stimulate such activities, and I am thankful to Emily Kelly and Alexander Navarini who helped me to publicise this study.

A 23-year old soldier who seemingly developed patches of
white hair within one day after he was injured by a mine.
(Lebar 1915)

A 6-year old horse that was supposedly found with a white
mane three days after it suffered a tremendous shock.
(McAlpine 1932)