The nightmare could have several meanings depending on the circumstances of the dream and your waking life. The first reason says that you are confessing some of your fears. The dream could also represent your past and the stressed youve experienced. You are experiencing some stressful situations at this point of your life. Sometimes the nightmares are created by the negative external causes such as drugs, narcotics, alcohol, sleepless nights.
Read more about dreaming of Nightmare in other dream meanings interpretations.