Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Dysautonomia ?
    ### Response:
    Dysautonomia refers to a disorder of autonomic nervous system (ANS) function that generally involves failure of the sympathetic or parasympathetic components of the ANS, but dysautonomia involving excessive or overactive ANS actions also can occur. Dysautonomia can be local, as in reflex sympathetic dystrophy, or generalized, as in pure autonomic failure.
    