Below is an instruction from Human. Write a response.
    ### Instruction:
    How to diagnose Narcolepsy ?
    ### Response:
    It can take as long as 10 to 15 years after the first symptoms appear before narcolepsy is recognized and diagnosed. This is because narcolepsy is fairly rare. Also, many narcolepsy symptoms are like symptoms of other illnesses, such as infections, depression, and sleep disorders.
    