THE EFFECTS OF SLEEP AND LACK OF SLEEP ON THE CEREBRAL CIRCULATION AND METABOLISM OF NORMAL YOUNG MEN 1

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Abstract
Studies of cerebral blood flow, cerebral vascular resistance, cerebral O2 consumption, mean arterial blood pressure, hemoglobin concentration, blood gases, and blood pH, were made before or after and during natural sleep in 6 subjects, during 2 consecutive determinations under identical conditions in 13 subjects, during a state of fatigue in 25 subjects, and also in 11 normal rested controls. Mean values obtained in rested subjects were almost identical with original normal values reported for the method. Fatigued subjects showed no differences from rested controls except for elevation in cerebral blood flow which approached statistical significance. During natural sleep there was a significant increase in cerebral blood flow, statistically significant decreases in cerebral vascular resistance and mean arterial blood pressure, and no changes in cerebral O2 consumption, hemoglobin concentration, and arterial O2 content. Fatigued subjects who slept were distinguished from those who were unable to sleep by higher values of CO2 tension and lower values of pH in arterial and cerebral venous blood even during the control period. Some relationship is suggested between respiratory acidosis and the process of falling asleep. Results of these studies make less tenable those hypotheses which attribute sleep to arterial anoxemia, cerebral ischemia, or to a generalized narcosis or other depression in cerebral metabolic rate.