Your hair needs energy from tiny power plants in cells (called mitochondria) to keep making pigment — without healthy mitochondria, your hair can't stay colored over time.

When the energy factories inside hair follicles don't work right, they make too many harmful molecules that damage the color-producing cells, making hair turn gray faster.

When the energy factories in our cells don't work right, they leak harmful particles that can damage hair color cells and cause gray hair to show up too early.

When your hair grows fast, it might stress the cells that give hair its color, causing them to wear out faster and turn hair gray sooner.

When a certain gene is turned off in hair color cells in mice, their fur starts to gray early because the cells die off — but the ones that survive can still make pigment just fine.

Too much stress from oxygen-related chemicals in your hair roots might damage the cells that give hair its color, leading to gray hair — especially when stuff like hydrogen peroxide builds up and harms those color-making cells.