Metabolic rate, respiratory exchange ratio, and apneas during meditation.

We tested the hypothesis that a drop in metabolic rate (MR) causes the apneas observed in some subjects during transcendental meditation (TM). We measured O2 consumption (VO2) and CO2 production (VCO2) in three groups of experienced meditators and one group of nonmeditating controls. Measurements were made before, during, and after TM for the meditators and before, during, and after eyes-closed relaxation for the nonmeditating controls. The three groups of meditators consisted of 1) those showing little change in the frequency of ventilation (f) with meditation, 2) those showing a marked decline in f, and 3) those showing numerous apneas and a marked fall in f. There were significant trial effects but no group or interaction effects for the decline in VO2. Thus we concluded that a drop in MR is not the cause of the apneas. However, there were significant trial and interaction effects for the changes in VCO2 and the respiratory exchange ratio (R), with a significant drop in R for the meditators but not for the controls. We report additional evidence and speculate that the drop in R is a consequence of mild hypoventilation.