Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Fatigue ?
    ### Response:
    Everyone feels tired now and then. Sometimes you may just want to stay in bed. But, after a good night's sleep, most people feel refreshed and ready to face a new day. If you continue to feel tired for weeks, it's time to see your doctor. He or she may be able to help you find out what's causing your fatigue and recommend ways to relieve it.
    