Abstract: A method and an apparatus for non-invasive detection of a physiological state or medical condition are disclosed. The method provides an indication of such state or condition such as myocardial ischemia or sleep apnea, by detecting the peripheral arterial tone's response to such state or condition, based on monitoring changes in peripheral arterial tone and determining that a change in the condition of the patient has occurred when a specific change in the peripheral arterial tone has been detected. A static pressure field is applied around the distal part of a digit of the subject. Peripheral arterial tone changes and related volume changes in the distal part of the digit are detected to thereby detect or monitor a physiological state or medical condition. The apparatus includes a finger probe (20), in the form of a tube (3) accommodating the patient's finger, which is designed to apply pressure, and a contiguous pressure cuff (40) which extends the boundary of the pressure field.