An overview of sleep after talking with Dr. Datta

Sleep is a "neurocratic" process. If democracy is rule by the people for the people and because of the people, then sleep is a neurocracy because it is done by the brain for the brain and because of the brain. Sleep is broken down into 5 main stages in humans with 5 distinct cortical EEG readings.

1. First, complete wakefulness involves sensory responses and high frequency, low amplitude neural activity.
2. Stage I sleep is the drowsy state right before sleep. The neural signal is slowing down, but the person may still have their eyes open (and in my case make basic responses to stimuli).
3. The start of stage II sleep is considered sleep onset by many polysomnograph technicians. In this type of sleep, the cortex makes sleep spindles and K-complexes. K-complexes are named for their distinctive shape in the EEG and they indicate a sensory response. A loud clap during a deeper stage of sleep will oftentimes show up as a K-complex in the EEG. Humans may also have a tS-R, or transition-to-REM sleep,  stage that looks just like stage II sleep without the K-complexes. Rats and cats have a distinctive tS-R which is distinguished because of pontine EEG readings from animals. If we could record EEG from the pons of humans without doing surgery, there is a good chance that humans also display this stage distinctively, too.
4. Slow wave sleep, or delta wave sleep is considered deeper sleep. Stage III and Stage IV sleep in humans are functionally equivalent; the only difference between the two stages is the prevalence of delta waves. In stage III sleep, delta waves make up 20-50% of the cortical activity. In stage IV sleep, the delta waves make up >50% of the cortical activity. These delta waves are extremely low frequency, high amplitude waves when measured by the EEG. 
5. REM sleep, called paradoxical sleep in France, makes up only ~20% of the sleep cycle. The rest (sometimes called NREM) is spent in the first 4 stages of sleep.  At the beginning of REM, people will move their heads before their body becomes paralyzed. REM is characterized by rapid eye movements, parasympathetic activation, autonomic disregulation, muscle atonia and cortical activation. Each of the sleep signs is regulated by a different nuclei in the mesencephalon. 

This is all information as I remember it from 2 hours ago, so the facts need to be checked. Look forward to the overview of Datta and Maclean 2007. That will reveal all!