The Two Distinct Stages Of Sleep

It may not seem like we are active when we are a sleep because most people would think of psychically being active and guess that when we sleep we aren’t active but while sleeping our brain is still active, when we dream our brain is as active as when we are awake. - What are the 2 distinct stages of sleep?
The 2 distinct stages of sleep are non-rapid eye movement (non-REM) and rapid eye movement (REM). - What device allows researchers to investigate the above stages?
Researchers are able to investigate REM and non-REM sleep by using an electroencephalogram also known as an EEG.
An electroencephalogram is a test that monitors electrical activity in your brain by attaching flat metal disc to your head and then the brain activity shows up