1. A monitoring device for monitoring inactive behavior of a monitored person in a monitored zone, comprising: a plurality of monitoring sensors configured to record sensor data, the plurality of monitoring sensors positioned in at least two spatially separated monitored subzones of the monitored zone; an evaluation device including a model module and a test module, wherein the model module is configured to: produce a first inactivity model of the monitored person in a spatially anonymized manner for a first time period with reference to sensor data in the first time period, produce a second inactivity model of the monitored person in the spatially anonymized manner for a second time period with reference to sensor data in the second time period, wherein at least portions of the second time period are formed later than the first time period, and wherein the test module is configured to: compare the first inactivity model and the second inactivity model and provide a change notification if there is a deviation between the first inactivity model and the second inactivity model.