Sometimes, multiple hairs on the same person's head go grey or even regain color at the same time — this might mean the body's internal systems are controlling hair color changes together.

When people go through stressful times, their hair might start to grey — and when stress goes down, some might actually see their hair regain color. This has been noticed to happen around the same time as changes in stress levels.

Your hair color comes from cells in your hair roots, and as you age, those cells slow down — that's why hair turns gray. But new research says things like stress might also play a role.