System for controlling access to a restricted area in a building, comprising: a sliding door system which comprises a door frame and a sliding door which can be displaced in the door frame between a closed position and an open position by means of a drive device, wherein the door frame has a passage region and a wall shell region which at least partially receives the sliding door in the open position, and wherein the sliding door has an inner door leaf facing toward the restricted area and an outer door leaf facing away from the restricted area, between which an interior space of the sliding door extends; a controller which is arranged on the sliding door and is communicatively connected to the drive device, wherein the controller is designed to control a movement of the sliding door between the closed position and an open position; and an activation device which is arranged in an interior space of the sliding door and is communicatively connected to the controller, wherein the activation device is designed to generate an activation signal when a user who wishes to leave the restricted area approaches the sliding door within a fixed distance, wherein the activation device detects an approach to the inner door leaf, and wherein the controller is designed to initiate a movement of the sliding door from the closed position to an open position when an activation signal is present, wherein the activation device comprises a first proximity sensor (54, 56) and a processing device connected thereto, wherein the processing device is communicatively connected to the controller, wherein the first proximity sensor (54, 56) comprises a first capacitive proximity sensor having a first conductive field plate arranged in the interior space on the inner door leaf, wherein the activation device comprises a second proximity sensor (56, 60) connected to the processing device and comprises a second capacitive proximity sensor having a second conductive field plate, wherein the second conductive field plate is arranged in the interior space on the inner door leaf, and wherein the first proximity sensor (54, 56) and the second proximity sensor (56, 60) are designed to detect an approach of the user and in each case to generate a detection signal, wherein the processing device is designed to process at least one of the detection signals. a sliding door system which comprises a door frame and a sliding door which can be displaced in the door frame between a closed position and an open position by means of a drive device, wherein the door frame has a passage region and a wall shell region which at least partially receives the sliding door in the open position, and wherein the sliding door has an inner door leaf facing toward the restricted area and an outer door leaf facing away from the restricted area, between which an interior space of the sliding door extends; a controller which is arranged on the sliding door and is communicatively connected to the drive device, wherein the controller is designed to control a movement of the sliding door between the closed position and an open position; and an activation device which is arranged in an interior space of the sliding door and is communicatively connected to the controller, wherein the activation device is designed to generate an activation signal when a user who wishes to leave the restricted area approaches the sliding door within a fixed distance, wherein the activation device detects an approach to the inner door leaf, and wherein the controller is designed to initiate a movement of the sliding door from the closed position to an open position when an activation signal is present, wherein the activation device comprises a first proximity sensor (54, 56) and a processing device connected thereto, wherein the processing device is communicatively connected to the controller, wherein the first proximity sensor (54, 56) comprises a first capacitive proximity sensor having a first conductive field plate arranged in the interior space on the inner door leaf, wherein the activation device comprises a second proximity sensor (56, 60) connected to the processing device and comprises a second capacitive proximity sensor having a second conductive field plate, wherein the second conductive field plate is arranged in the interior space on the inner door leaf, and wherein the first proximity sensor (54, 56) and the second proximity sensor (56, 60) are designed to detect an approach of the user and in each case to generate a detection signal, wherein the processing device is designed to process at least one of the detection signals.