Why your hair turns grey is simpler than you think.
Your follicles rely on a stem cell reserve to keep churning out pigment cells, but that supply eventually runs dry. Stress can accelerate this depletion, and no, plucking them out won’t fix the underlying issue.
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Since someone will ask: yes, there is human evidence on stress and grey hair, and it's more interesting than "it was in mice" suggests.
A 2021 study mapped the colour along individual hairs, a bit like tree rings, in 14 people. Grey sections lined up with stressful periods in their lives, and some hairs actually got their colour BACK when the stress eased.
Before anyone gets excited: that's 14 people, it's a correlation, and the reversal was in people who were only just starting to go grey. It does not mean de-stressing will undo grey hair you already have. A strong lead, still not a proven fact about your head.
Not on me.
Every hair that's turned gray on me, I've watched the browns inside of it appear to pull backwards inside the hair and in the end it is a desiccated Hollow tube that pulls out of the follicle easier than the full color hairs.