Here's why:
* Hair color is determined by melanin: The pigment that gives hair its color is called melanin. As we age, the production of melanin slows down, causing hair to gradually lose its color and turn grey or white.
* Fear and stress don't directly change melanin production: While stress can contribute to overall health and affect things like sleep, diet, and immune function, it doesn't have a direct impact on melanin production.
* The "instant" whitening is a visual effect: Sometimes, during extreme stress or trauma, people might experience a noticeable increase in the amount of white hairs they see. This is usually due to the stress causing existing grey hairs to become more prominent, not because new white hairs are suddenly appearing.
In short, while fear and stress can impact your health, it's impossible for them to instantly turn your hair white.