In a dazed, disoriented, confused state; inattentive: He was so tired he was walking around in a haze(1888+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with in a fog
in a fog
Also,in a haze. Preoccupied, not paying attention; also, at a loss, confused. For example, After the accident he went about in a fog, even though he had not been injured, or Millie always seems to be in a haze; she never knows what's going on. These expressions allude to fog or haze obscuring one's view; the fog usage dates from about 1600, haze from about 1800.