What are the four d"s of negligence? and explain each one

Duty: duty exists when the physician-patient relationship has been established. The patient has sought the assistance of the physician and the physician has knowingly undertaken to provide the needed medical service.
dereliction: failure to perform a duty is the second element required there must be proof that the physician has somehow neglected the duty of the patient.
direct cause: there must be proof that the harm to the patient was directly caused by the actions of the physicians or the failure to act and that the harm would not have otherwise occurred.
damages: the patient must prove that a loss or harm has resulted has resulted from the actions of the physician. 
       Hope that helped! :)

They probably don't understand either 1. what the nightmare is about or 2. his anxiety and stress