Regional cerebral glucose metabolism in man during wakefulness, sleep, and dreaming

Regional cerebral glucose metabolism was measured by positron emission tomography in 4 healthy male volunteers, both during wakefulness and sleep, using the 2-deoxy-D-[2-18F]glucose method. While 3 of the subjects did not report dreaming and, during sleep stages I-IV of variable duration, exhibited a non-selective decrease in metabolic rates averaging 12.6 +/- 4.73% (mean +/- S.D.) for the entire brain, the fourth volunteer who experienced an extended nightmare during his sleep examination showed a generalized increase in cerebral glucose utilization ranging from 2.1% in lentiform nucleus to 30.0% in the superior frontal cortex, with a weighted whole brain average of 16.4%. These findings suggest that energy metabolism in the human brain is generally depressed during slow-wave sleep as opposed to a--possibly differential--activation during dreaming.