A sensor and system for observing the presence, location, movement and/or attitude of one or more objects to be monitored includes a sensor detecting presence, location, movement and/or attitude. The sensor includes two detectors, which are adapted to measure in two measuring ranges that are at a different height, of which the measuring range of the first detector is a lower measuring range and the measuring range of the second detector is an upper measuring range. The sensor further includes a third detector, which is adapted to detect an item, such as a towel or clothing article, placed in front of and/or on top of the first detector, second detector and/or third detector.