There are factors that affect how anesthesia can quickly leave the body and these are age and health and the type and strength of anesthesia used. For instance, Midazolam is a long lasting sedative and this is usually used as an anesthetic. 98% of which can leave the bloodstream after 15 hours. http://howlongguide.com/how-long-does-anesthesia-stay-in-your-body/
Anesthesia usually wears off several hours after it is administered. However, this varies depending on the type of anesthesia, the amount administered, and the health of the individual being given anesthesia.