Hair turning gray over night?

Have you ever heard of an adult's hair turing gray/white overnight or in a very short period of time due to emotional stress or grief?

Hair turning gray over night?

Yes. My grandmother who lost a lot of her children when babies went gray overnight. Apparently what happens is, stress causes the hair to fall out and as gray hairs are stronger they remain. This looks like the hair has turned gray over night when in reality stress has caused the colored hair to fall out. I have no idea if that is true I just read it some where.

Edit

I just fond this link and apparently hair can not go gray overnight.http://psychologytoday.com/articles/pto-...