Hair turns grey when the cells that give it colour, called pigment cells, slow down or stop making pigment. These pigment makers sit near the base of each hair follicle and supply Grey Hair: What Causes It, And Can It Be Reversed? A Scientific Analysis A Recent Study Finds That It May Be Possible To Reverse Gray Hair Most people think grey hair is just aging, but your biology sends the signal long before the color changes. Researchers have already mapped out the internal pathways that switch pigment on or