Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Obesity Hypoventilation Syndrome ?
    ### Response:
    Obesity hypoventilation syndrome (OHS) is a breathing disorder that affects some obese people. Why these people develop OHS isn't fully known. Researchers think that several factors may work together to cause OHS. These factors include:
                
A respiratory (RES-pih-rah-tor-e) system that has to work harder than normal and perhaps differently because of excess body weight.
    