A method for monitoring a physiological signal monitors the sleeping quality of a person under sleep test with long hours in daily life at home. The system comprises a distributed data server, at least one physiological signal sensor, and at least one computer. The sensor is wired or wirelessly connected to the server. The server connects on Internet to the computer. The sensor transmits the sensed physiological signals to the server to process, calculate, analyze, and store. By means of physiological signal data processing, the computer further calculates and analyzes the physiological signal data stored in the server and allows an authorized reader to read the result. With the household sensor working with the server connecting to Internet, the system may be available in daily life at home to monitor the sleeping quality of the person under sleep test with long hours.