a system is shown for detecting the movements of a patient confined to a bed so as to determine if there is the likihood that the patient is trying to leave the bed . a sensor is arranged to be placed under the mattress of a bed next to the frame and is totally sealed from the intrusion of contaminants so that it is not necessary to discard the sensor after a patient is discharged . the sensor utilizes ribbon switches sandwiched in assembly between stiff plexiglas plates . the assembly is sealed in a bag that holds the parts in assembly while permitting relative movement in all directions . the alarm system is arranged so that if the sensor detects undesired patient movement , the regular nurses &# 39 ; call light system is deactivated and an alarm distinguishable therefrom is superimposed on the nurses &# 39 ; call light alarm . in addition , an alarm audible to the patient encourages the patient to return to the desired position on the bed . the system then returns to normal and the alarms cease so that resetting is not necessary . other alarms are activated at remote locations . a bed rail activated switch is utilized to arm and disarm the system so that if the bed rail is lowered to remove a patient from the bed , the alarms are not activated and when a patient is replaced on the bed and the rail is raised , the system is reactivated .