Over-processing your hair with hair coloring, bleaching, heat styling can dissolve the protective layer on hair strands, resulting in damage to the hair cuticle. Your weakened hair strands become dull, thin, brittle, and easily breakable. So the harm is on both scalp and hair. It is highly recommended to treat your scalp as well as your hair. Choose a natural hair product to restore the moisture and strengthen the cuticle. Avoid chemical-based ones as they might worsen the damage.