A seat monitoring system comprises a first layer of one or more fluid bladders packaged within a seat, a pump in fluid communication with the first layer, the pump operable to increase fluid pressure of each bladder within the first layer, an array of one or more sensors in fluid communication with the first layer and operative to sense pressure and pressure changes within each bladder within the first layer and a controller configured to: collect pressure data; determine from the pressure data a monitored parameter relevant to a subject in the seat; and change an aspect of the seat based on the monitored parameter. Methods of using the seat monitoring system can include determining a drowsiness threshold and altering a user that he or she is getting drowsy.