Stupor is characterized by impaired reaction to external stimuli. Those in a stuporous state are rigid, mute and only appear to be conscious, as the eyes are open and follow surrounding objects. If not stimulated externally, a patient with stupor will appear to be in a
sleepy state most of the time. In some extreme cases of severe depressive disorders the patient can become motionless, lose their appetite and become mute. Short periods of restricted responsivity can be achieved by intense
stimulation (e.g. pain, bright light, loud noise, shock). == Causes ==