RT Book, Section A1 Raj, Kristin S. A1 Williams, Nolan A1 DeBattista, Charles A2 Papadakis, Maxine A. A2 McPhee, Stephen J. A2 Rabow, Michael W. SR Print(0) ID 1175782881 T1 Sleep-Wake Disorders T2 Current Medical Diagnosis & Treatment 2021 YR 2021 FD 2021 PB McGraw-Hill Education PP New York, NY SN 9781260469868 LK accessmedicine.mhmedical.com/content.aspx?aid=1175782881 RD 2023/02/08 AB Sleep consists of two distinct states as shown by electroencephalographic studies: (1) REM (rapid eye movement) sleep, also called dream sleep, D state sleep, or paradoxic sleep, and (2) NREM (non-REM) sleep, also called S stage sleep, which is divided into stages 1, 2, 3, and 4 and is recognizable by different electroencephalographic patterns. Stages 3 and 4 are “delta” sleep. Dreaming occurs mostly in REM and to a lesser extent in NREM sleep.