In the past I dyed my hair to cover the grey, but it became a more frequent event so I decided to just go grey. My hair has been almost entirely white for nearly 20 years. The pigment has been returning to my hair gradually for the last 18 months. Do you have any explanation for this? I have tried to research this, but have not found any answers. There is information for reasons why hair looses pigmentation, but not for its return. Any ideas?