We report studies on the development of a new approach to investigating behavior-associated brain energy metabolism (EM), initiated by ourselves. The essence of this approach is the use of implanted platinum electrodes for the simultaneous multipoint monitoring of local changes in redox potential (E) of the cerebral cortex in freely mobile animals in chronic experimental conditions. Polarigraphic recording of cortical E, the electrocorticogram (ECoG), and movement activity in freely mobile animals during slow-wave sleep (SWS) showed that the transition from waking to SWS in rats was accompanied by changes in metabolic activity at cortical points, with decreases in E and the appearance of a complex of oscillations in E, forming the background for the appearance of irregular periodic twitches (with intervals of 3–40 sec), which were accompanied by ECoG activation and waves of decreased E. Reported data indicate that episodes of ECoG activation during SWS are accompanied by decreases in pO2 in rat brain tissue. Light and sound presented to humans during SWS decrease oxygenation levels in a number of brain areas. Overall, these points provide evidence that both SWS and episodes of cortical activation during SWS are associated with increases in the intensity of functional units largely using glycolysis as energy source. Published data indicate that the main aerobic glycolysis compartment consists of the astroglia. This suggests that the astroglia play a particularly important role in processes occurring during SWS.