Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Insomnia ?
    ### Response:
    Secondary Insomnia
                
Secondary insomnia is the symptom or side effect of another problem. This type of insomnia often is a symptom of an emotional, neurological, or other medical or sleep disorder.
                
Emotional disorders that can cause insomnia include depression, anxiety, and posttraumatic stress disorder.
    