Indigo leaves cooked in coconut oil can be used as a home cure for greying hair in addition to being used as a natural hair colour in powder form. Long-term usage of this combination can not only reverse but even prevent hair greying. A sort of communication impairment is receptive language dysfunction. People who have it frequently do not comprehend what others are saying. They struggle with the meaning of words and may respond in illogical ways. Their difficulties, however, are unrelated to hearing loss or IQ. Rather, they result from problems with grammar and vocabulary processing at the brain level. Receptive language disorder often leads to delays in speech development and learning. Children may say single words but not sentences. Others may know how to write but cannot speak correctly. There are different types of receptive language disorders and they can be identified by specific tests. The good news is that most people who suffer from this problem can learn how to improve their skills with appropriate training. Indigo has been used for hair color since 1856 when William Henry Perkin first produced it. It was originally called "mauve" but this name was soon changed because there was already another chemical named mauve. Indigofera tinctoria, which produces indigo, comes from the family Fabaceae (or Leguminosae). It is believed that using indigo for hair color prevents hair graying because it inhibits an enzyme called tyrosinase which is responsible for producing melanin in skin cells. Too much of this enzyme can cause hyperpigmentation and darkening of hair follicles resulting in grey hair.