An impairment in the clarity of consciousness characterised by impaired ability to comprehend aspects of the environment or the self in relation to the environment, inattention, and abnormalities in thought processes, comprehension. It is typically accompanied by subjective experience of mental clouding described as feeling ‘foggy’. Clouding of consciousness is a common form of cognitive disturbance in Delirium, but it is not synonymous with Delirium because Delirium includes additional diagnostic requirements.