Non-REM

Non-REM has a couple stages of its own:

1. Light Sleep: The initial stage of sleep. It is quite easy to be woken up during this phase because you are not in a deep sleep.


2. True Sleep: Heart rate and breathing slows significantly. (Process last for nearly 20 minutes)


3. Deep Sleep 1: Heart and breathing rates continue to lessen and the brain begins a session in which produces Delta Waves.


4. Deep Sleep 2: Muscle activity is the lowest. (As a result, waking up can make you groggy or heavy)