Conscious patients undergoing regional anaesthesia are able to interact with caregivers and indicate when they are feeling pain and/or anxiety during surgery. Unconscious patients on the other hand, not only in the operating room but also in intensive care, need antinociception when a nociceptive stimulus is applied. In these patients, the dose of antinociceptive drugs cannot be adjusted or the effect of locoregional anaesthesia supplementing general anaesthesia cannot be determined by simply asking the patient. Thus, the clinician needs to rely on monitors of the nociception/antinociception (N/AN) balance to be able to provide adequate, that is personalized, antinociception.