Which device can indicate whether someone is in stage 1,2,3,or 4 of sleep?

Question

Which device can indicate whether someone is in stage 1,2,3,or 4 of sleep?​

Quizplus · Accepted Answer

EEG (Electroencephalogram) is the device that measures electrical activity in the brain. It can identify the different stages of sleep based on the patterns of brain activity, such as slow waves and rapid eye movement. MRI, IAT, and PET are imaging techniques that provide information on brain structure and function, but they are not capable of identifying sleep stages.

Which Device Can Indicate Whether Someone Is in Stage 1,2,3,or