A sleep monitoring apparatus includes a plurality of sensor modules, a transceiver, and a processor operatively coupled with the plurality of sensor modules and the transceiver. The processor is configured to receive, from the plurality of sensor modules, raw sensor data for each of the plurality of sensor modules related to a sleep session of a user of the sleep monitoring apparatus, and perform raw data fusion of the raw sensor data. The raw data fusion generates a fused raw data signal. The processor is further configured to, based on the fused raw data signal, perform feature extraction for the plurality of sensor module; based on the feature extraction, perform feature fusion for the plurality of sensor modules; based on the feature fusion, perform decision fusion for the plurality of sensor modules; and determine a sleep stage of the user based on the decision fusion.