Pigment Production

Locks of gray hair
Q: I'm a 33 years old woman who has some grey hairs, but I have found many that are half way grey from the tip to the middle, having the other half (all the way to the root) my natural brunette color.
Isn't it supposed to be the other way around? If the hair bleaches itself inside and comes out grey, how come some of my grey hairs have dark roots with totally white tips? I don't color my hair so can you explain to me how this happens?

A: Actually there is no law that says the follicle that stops producing pigment will NEVER resume pigment production. In fact, many different causes can be responsible for the cessation of pigment production, some of which can be temporary or sporadic.
This could explain the color oddities of the strands of your hair. (In some cases, people find that their hair develops alternating bands of color and lack-of-color from repeated on-and-off pigment production.)
Aside from this possibility, there is the fact that if the ends of the hair become more porous, the pigment can be lost from the ends of the hair that are most porous and retained where the cuticle is tighter and smoother.
I know that recently, my own mother, whose hair I have been doing for decades, has shown less gray in her new growth between color treatments. She'd been being treated for some health and hormonal problems and I believe that either the resolution of the health issues or the effect of certain medications has caused her to restart producing pigment in certain hairs again.
I would love to give you a more concrete answer, but the fact is that there are many factors that can play a part in the way the hair goes gray. If the situation worries you, you could consult a dermatologist to see if there's anything that could be causing an unusual biological reaction. And especially if there are other symptoms such as if you feel a change in the texture of your hair, or if you have any scalp sensitivity or irritation, then I would recommend you consult a dermatologist.
My personal though is that it's a reactivation of pigment production. However, please never take the opinion of a hairdresser as medical advice. If you are concerned about medical repercussions, then by all means, see your doctor.
Photo: Ilya93/Shutterstock
See also:
Why and how does hair turn grey?
Medications and the possible effect on your hair
My hair color is going darker instead of grey. Why is this happening?
Is there any known natural remedy which can reverse gray hair?