abnormal sleep pattern abnormal non-rapid eye movement sleep pattern csmith 2013-11-14T13:01:55Z MPheno.ontology NREM sleep was divided into four stages in the Rechtschaffen and Kales (R&K) standardization of 1968. That has been reduced to three in the 2007 update by The American Academy of Sleep Medicine (AASM), combining the previous stage 3 and 4 to a single stage 3 also known as deep sleep or slow-wave sleep. The three stages that comprise NREM sleep account for 75-80 percent of total sleep time in humans. MP:0012289 abnormal NREM sleep pattern any anomaly in the frequency or duration of the sleep stages characterized by distinct EEG patterns, decreased metabolic activity, slowed breathing and heart rate, and the absence of rapid eye movement and dreaming