Gray hair is a typical sign of getting older. Or is it? In fact, there are also many young people who are starting to get their first gray hairs. Researchers have discovered that stress is one of the main causes of gray hair. A stressful lifestyle can affect certain stem cells in the hair follicle. These are directly linked to the production of color pigments in the hair. The result: the hair that grows back is white. A lack of melanin is also responsible for the development of gray or white hair. You read that correctly: when hair turns gray, it turns white on closer inspection. Over the years, the cells in our hair roots lose their ability to produce the pigments that give hair its color. This is why colorless or white hair grows back. However, because this process does not occur simultaneously in all hair cells, white hair mixes with those that still contain color particles. The result is the "gray hair effect."