A method and system for automatically determining bed-time periods are disclosed. The method comprises detecting at least one physiological signal, determining a posture angle and an activity level using the at least one detected physiological signal, and determining a bed-time period using both the posture angle and the activity level. The system includes at least one sensor to detect a plurality of physiological signals, a processor coupled to the at least one sensor, and a memory device coupled to the processor, wherein the memory device includes an application that, when executed by the processor, causes the processor to detect a posture angle using at least one of the plurality of detected physiological signals and to determine a bed-time period using both the posture angle and the activity level.
