<prompt> Waves on EEG during stage 4-NREM period of sleep is: RepeatAlphaBetaDeltaTheta  <response>: Ans: C Delta Ref: Pal GK, Reticular Formation, EEG and Steep, In: Textbook of Medical Physiology, Ahuja Publishing House 2007: 119:895Explanation:Non - REM Sleep Slow Wave SleepStage 1Beta to alpha rhythmStage 2Amplitude increasesSleep spindle 12-14Hz; 50pV; for about 2 Seconds and K complexes high amplitude Stage 3High amplitude; low frequencyStage 4Delta rhythmAutonomic and visceral changes- heart rate and BP body temperatureSlow regular respiration Gf activity muscle toneNo rapid eye movement 