FIELD : medicine.SUBSTANCE : group of inventions relates to medicine. Method of monitoring vital signs of a subject is carried out using a device with a sensitive element for monitoring vital signs of a subject. Signal of the sensitive element, which is a vital activity indicator, is measured. Signal evaluation unit is used to evaluate signal based on previously measured signals, unsuccessful measurement or unreliable signal of sensitive element. It is controlled by a signal measurement control unit to automatically change the measurement interval depending on the evaluation result. Repeating signal measurements for a predetermined time interval or a predetermined number of times, or until measurement is successful or signal of sensitive element is not reliable, if unsuccessful measurement or unreliable signal of sensitive element was identified. One of the measured signals of the sensitive element is transmitted, even if all measurements were unsuccessful or all the measured signals of the sensitive element are unreliable. If all measurements were unsuccessful or all measured signals of sensitive element are unreliable, measurement control is continued. Repeating signal measurement of sensitive element for additional preset period. Transmitted signal of the sensitive element is replaced with a new signal measured during the additional period, if during that period the measurement was successful or the reliable signal of the sensitive element was measured.EFFECT : enabling optimization with respect to energy consumption and measurement.17 cl, 4 dwg