The idea that perioperative outcomes may be improved through the implementation of measures that modify the surgical stress response has been around for several decades. Many techniques have been trialled with varying success. In addition, how the response to modification is measured, what constitutes a positive result and how this translates into clinical practice is the subject of debate. Modification of the stress response is the principal tenet behind the enhanced recovery after surgery (ERAS) movement which has seen the development of guidelines for perioperative care across a variety of surgical specialties bringing with them significant improvements in outcomes.