Apparatus for assessing the reliability of a measurement of blood pressure of a subject, comprising: a control unit configured to: obtain a first measurement of at least one physiological characteristic of the subject that is indicative of the level of pain and/or stress of the subject, wherein the first measurement is made prior to a measurement of blood pressure being made; obtain the measurement of blood pressure of the subject; obtain a second measurement of the at least one physiological characteristic of the subject, wherein the second measurement is made after the measurement of blood pressure is made and prior to a subsequent measurement of blood pressure being made; and determine if the measurement of blood pressure is reliable based on the first measurement and the second measurement, wherein the measurement of blood pressure is determined to be reliable if the first measurement of the at least one physiological characteristic and the second measurement of the at least one physiological characteristic indicate a low level of pain and/or stress and wherein the measurement of blood pressure is determined to be not reliable if the first measurement of the at least one physiological characteristic and the second measurement of the at least one physiological characteristic indicate a different level of pain and/or stress prior to the measurement of blood pressure being made to the level of pain and/or stress indicated after the measurement of blood pressure is made; an inflatable cuff for use around a limb of the subject; a pump for inflating the cuff; and a pressure sensor for measuring the air pressure inside the inflatable cuff; wherein the inflatable cuff further comprises a physiological characteristic sensor for obtaining measurements of the at least one physiological characteristic; and wherein the physiological characteristic is heart rate variability or skin conductance/conductivity. a control unit configured to: obtain a first measurement of at least one physiological characteristic of the subject that is indicative of the level of pain and/or stress of the subject, wherein the first measurement is made prior to a measurement of blood pressure being made; obtain the measurement of blood pressure of the subject; obtain a second measurement of the at least one physiological characteristic of the subject, wherein the second measurement is made after the measurement of blood pressure is made and prior to a subsequent measurement of blood pressure being made; and determine if the measurement of blood pressure is reliable based on the first measurement and the second measurement, wherein the measurement of blood pressure is determined to be reliable if the first measurement of the at least one physiological characteristic and the second measurement of the at least one physiological characteristic indicate a low level of pain and/or stress and wherein the measurement of blood pressure is determined to be not reliable if the first measurement of the at least one physiological characteristic and the second measurement of the at least one physiological characteristic indicate a different level of pain and/or stress prior to the measurement of blood pressure being made to the level of pain and/or stress indicated after the measurement of blood pressure is made; obtain a first measurement of at least one physiological characteristic of the subject that is indicative of the level of pain and/or stress of the subject, wherein the first measurement is made prior to a measurement of blood pressure being made; obtain the measurement of blood pressure of the subject; obtain a second measurement of the at least one physiological characteristic of the subject, wherein the second measurement is made after the measurement of blood pressure is made and prior to a subsequent measurement of blood pressure being made; and determine if the measurement of blood pressure is reliable based on the first measurement and the second measurement, wherein the measurement of blood pressure is determined to be reliable if the first measurement of the at least one physiological characteristic and the second measurement of the at least one physiological characteristic indicate a low level of pain and/or stress and wherein the measurement of blood pressure is determined to be not reliable if the first measurement of the at least one physiological characteristic and the second measurement of the at least one physiological characteristic indicate a different level of pain and/or stress prior to the measurement of blood pressure being made to the level of pain and/or stress indicated after the measurement of blood pressure is made; an inflatable cuff for use around a limb of the subject; a pump for inflating the cuff; and a pressure sensor for measuring the air pressure inside the inflatable cuff; wherein the inflatable cuff further comprises a physiological characteristic sensor for obtaining measurements of the at least one physiological characteristic; and wherein the physiological characteristic is heart rate variability or skin conductance/conductivity.