Final answer:
The gold standard in sleep research typically involves a comprehensive set of measurements, including EEG, EOG, EMG, EKG, as well as respiration and skin conductance, among others.
Step-by-step explanation:
The gold standard in sleep research often involves comprehensive polysomnography, which includes not only an EEG (electroencephalography) to measure brain waves, but also additional measurements such as EOG (electrooculography) to record eye movements, EMG (electromyography) to assess muscle activity, and EKG (electrocardiogram) to monitor heart rate and rhythm. Moreover, it could include sensors for respiration, skin conductance, and more to fully capture the physiological state during sleep. Thus, option (3) EEG, EOG, EMG, EKG and respiration, skin conductance, vasoconstriction, etc. can be considered a comprehensive approach in sleep studies.