Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Cyclic Vomiting Syndrome ?
    ### Response:
    Cyclic vomiting syndrome, sometimes referred to as CVS, is an increasingly recognized disorder with sudden, repeated attacksalso called episodesof severe nausea, vomiting, and physical exhaustion that occur with no apparent cause. The episodes can last from a few hours to several days.
    