Correlations using the NREM-REM sleep cycle frequency in healthy humans support distinct regulation mechanisms for REM and NREM sleep

REM sleep cycle frequency support distinct regulation mech-anisms for REM and NREM sleep. J Appl Physiol 93: 141–146, 2002. First published February 22, 2002; 10.1152/ japplphysiol.00917.2001.—Polysomnograms of most homeo-thermic species distinguish two states, rapid eye movement (REM) and non-REM (NREM) sleep. These alternate several times during the night for reasons and following rules that remain poorly understood. It is unknown whether each state has its own function and regulation or whether they repre-sent two facets of the same process. The present study com-pared the mean REM/NREM sleep ratio and the mean num-ber of NREM-REM sleep cycles across 3 consecutive nights. The rationale was that, if REM and NREM sleep are tightly associated, their ratio should be comparable whatever the cycle frequency in the night. Twenty-six healthy subjects o