Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Narcolepsy ?
    ### Response:
    Narcolepsy is a chronic brain disorder that involves poor control of sleep-wake cycles. People with narcolepsy have episodes of extreme daytime sleepiness and sudden, irresistible bouts of sleep (called "sleep attacks") that can occur at any time, and may last from seconds or minutes.
    