Change in the Concentration of Lactic Acid in the Rat and Hamster Brain during Natural Sleep

Richter and Dawson 1 first reported that young rats killed by immersion in liquid nitrogen during natural sleep showed a decrease in the concentration of lactic acid in the brain when compared with control animals in the normal waking state, but experimental confirmation of this finding has not been published. Shimizu et al. 2 have recorded a failure to confirm it in experiments involving brief periods of sleep.