After how many hours does the patient be conscious after operation?

Clarify: Please clarify what operation and what type of anesthesia. Also, please re-phrase the question. The recovery time after surgery is highly variable depending on the surgery done and the anesthesia used.

Variable: Duration of unconsciousness after surgery varies depending on the patients physiology and how they process the drugs used and on the drugs used and amount of drugs used. There could be no unconsciousness if there is a spinal or local anesthesia used. Some patients are kept in a inducted coma state for extended periods of time if needed for there condition.