Be very worried or upset by. For example, I know I'm going to get gray hair from his driving. Similarly, give gray hair to means “to worry someone,” as in The boy's love of rock climbing gave his parents gray hair. This idiom alludes to the notion that extreme anxiety or grief can cause one's hair to turn gray. [Early 1600s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.