 The most dangerous aspects of narcosis are the impairment of judgement , multi @-@ tasking and coordination , and the loss of decision @-@ making ability and focus . Other effects include vertigo and visual or auditory disturbances . The syndrome may cause exhilaration , giddiness , extreme anxiety , depression , or paranoia , depending on the individual diver and the diver 's medical or personal history . When more serious , the diver may feel overconfident , disregarding normal safe diving practices . 
