Jeff, Kirsten, and other hairy tipsters:
I would have said until last week that the "turn white overnight" or
"gray overnight" stories were the veriest nonsense. Happens that a
local M.D. did the subject on a radio "good question" segment a few
days ago. He claimed that various kinds of emotional stress (perhaps
via reduced ability to combat disease) can cause hair loss (quickly,
perhaps not really "overnight"), and that for some reason, poorly
pigmented hair (which is there all along) is thereby revealled. (I dunno
if the gray/white hairs fall out disproportionately less, or if they just
show up more in an overall thinner thatch.) Same guy said that
hair pigmentation is essentially applied to the outside of growing hairs
by a mechanism separate from the one that makes 'em grow -- and the
pigmenter usually poops out with aging before the grower. (I wasn't
clear if the pigmenter was also more susceptible to things like stress
than the grower, but that might help the "overnight white" story.)
Can't vouch for the truth of all this but I can present some evidence
that I have no personal axe to grind -- see the bald guy at
http://www.unb.ca/psychology/likely/samples/about_the_author.htm
-David
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David G. Likely, Department of Psychology,
University of New Brunswick
Fredericton, N. B., E3B 5A3 Canada
History of Psychology:
http://www.unb.ca/web/psychology/likely/psyc4053.htm
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