<prompt> A 72-year-old woman with insomnia paicipates in a sleep study . As pa of the study protocol, she has EEG leads attached, then goes to sleep. At one point during the evening, 12-16 Hz sleep spindles and K-complexes are observed. Which of the following stages of sleep is associated with this pattern?REMStage 1Stage 2Stage 3  <response>: Stage 2 has more theta waves than stage 1 and is associated with sleep spindles sho bursts of 12-16 Hz activity and K-complexes high amplitude slow waves with superposed sleep spindles on the electroencephalogram. Transient large amplitude potentials in the occipital areas ponto-geniculo-occipital spikes are associated with REM sleep. Stage 1 or drowsiness, is characterized by the attenuation of alpha rhythm 8-13 Hz and the appearance of 4-7-Hz theta waves. Stages 3 and 4, or slow wave sleep, are characterized by high amplitude slow waves, especially in the delta 4 Hz frequency range. 