What does it mean when you dream that a black cobra is after you?

Chase dreams often indicate that the dreamer is running from some problem or situation in real life. The subconscious presents an image of the dreamer literally running away. In this dream, the problem is symbolized by a cobra, suggesting the serious nature of the situation. Being chased in one's own house suggests that the problem is something within the dreamer's personal life, such as a medical issue or a close relationship.

Our sleeping posture is also one of the reason for fearful dreams. If blood circulation is restricted due to wrong sleeping posture, our brain simulates such a horrible dream so that individual will come to waking state.

... Where as individual will be brought to waking state by scary dreams.