A patient monitoring and repositioning system in combination with a bed having a deck, comprising: a mattress residing on the deck and having a head end, a foot end, and an upper surface; a sheet residing on the upper surface; a drive mechanism located near the head end of the mattress and operable to pull the sheet toward the head end of the mattress to thereby reposition the sheet relative to the mattress, and also reposition a patient residing on the sheet; characterized in that the system comprises: a housing containing the drive mechanism, the housing including a slot extending therealong, and the drive mechanism being operable to pull the sheet into the housing via the slot, the housing further including an access door movable relative to the housing to thereby permit access to the inside of the housing; and a sensor arrangement (12; 112a) operatively connected to the drive mechanism, the sensor arrangement being configured to sense a position of the patient relative to the mattress on the bed over substantially the entire top surface of the mattress, and to generate a signal in response to the patient moving from a predetermined position, and the drive mechanism being configured to pull the sheet so as to reposition the patient to the predetermined position upon receiving the signal from the sensor arrangement, wherein the predetermined position is a desirable position and/or range of positions relative to the mattress in which the patient, resting on the mattress, benefits from a reduced likelihood of injury, such as by pressure ulcers, and an increased likelihood of patient comfort. a mattress residing on the deck and having a head end, a foot end, and an upper surface; a sheet residing on the upper surface; a drive mechanism located near the head end of the mattress and operable to pull the sheet toward the head end of the mattress to thereby reposition the sheet relative to the mattress, and also reposition a patient residing on the sheet; characterized in that the system comprises: a housing containing the drive mechanism, the housing including a slot extending therealong, and the drive mechanism being operable to pull the sheet into the housing via the slot, the housing further including an access door movable relative to the housing to thereby permit access to the inside of the housing; and a sensor arrangement (12; 112a) operatively connected to the drive mechanism, the sensor arrangement being configured to sense a position of the patient relative to the mattress on the bed over substantially the entire top surface of the mattress, and to generate a signal in response to the patient moving from a predetermined position, and the drive mechanism being configured to pull the sheet so as to reposition the patient to the predetermined position upon receiving the signal from the sensor arrangement, wherein the predetermined position is a desirable position and/or range of positions relative to the mattress in which the patient, resting on the mattress, benefits from a reduced likelihood of injury, such as by pressure ulcers, and an increased likelihood of patient comfort. a housing containing the drive mechanism, the housing including a slot extending therealong, and the drive mechanism being operable to pull the sheet into the housing via the slot, the housing further including an access door movable relative to the housing to thereby permit access to the inside of the housing; and a sensor arrangement (12; 112a) operatively connected to the drive mechanism, the sensor arrangement being configured to sense a position of the patient relative to the mattress on the bed over substantially the entire top surface of the mattress, and to generate a signal in response to the patient moving from a predetermined position, and the drive mechanism being configured to pull the sheet so as to reposition the patient to the predetermined position upon receiving the signal from the sensor arrangement, wherein the predetermined position is a desirable position and/or range of positions relative to the mattress in which the patient, resting on the mattress, benefits from a reduced likelihood of injury, such as by pressure ulcers, and an increased likelihood of patient comfort.