Apparatus (10) is provided that includes at least one sensor (30), configured to sense a physiological parameter of a subject (12) and to sense large body movement of the subject (12), an output unit (24), and a control unit (14). The control unit (14) is configured to monitor a condition of the subject (12) by analyzing the physiological parameter and the sensed large body movement, and to drive the output unit (24) to generate an alert upon detecting a deterioration of the monitored condition. Other embodiments are also described.