Answer:. e)evolutionary
Explanation: Due to the gradual development of the human , it is seen the changes that occur in the human being as evolution. The change in sleep pattern due to any factor that scares a person especially during the darkness is also a part of evolution .This is the time that a person can develop certain thoughts that can alter the sleep pattern such as tiredness due to work, haunting thought, phobia of darkness etc.
So, the correct option is option(e).