Dr. Dorian is running their very first sleep study. The goal of this study is to analyze time spent in REM sleep following sleep deprivation. Which of the following tools will help Dr. Dorian determine whether a subject is in REM sleep vs awake in their study?
1) An Electro-Encephalo-Gram to measure brain activity.
2) An Electro-Myo-Gram to measure muscle activity.
3) An Electro-Oculo-Gram to measure eye activity.
4) Absorbent pads to measure sweat rate.