Can your hair turn white as a result of shock?

Theoretically, any sudden severe shock, accident, illness or change in metabolism could make hair change colour, but it won't be visible right away.

According to Dr John O'Connor, head of the School of Physical Science and Mathematics at the University of Newcastle in Australia, "once your hair has grown out of its follicle, any emotional or physical trauma will not affect it. This hair is basically dead, like your nails. Yet severe adverse events could cause new hair that grows out a few weeks later to be white."

The Register, Can your hair turn white as a result of shock?, 2006