What Happens When We Fall Asleep
It was the Friday before Thanksgiving, and I had not slept on Thursday night. I was engaged to play piano the following day, and therefore determined to sleep. However, I was scared of the myoclonic jerks which accompany sleep, as they are difficult to distinguish from a seizure. I didn't want to have a seizure, as I didn't want (in the worst scenario) to die; I still had several things to live for.
And so it was that I fell asleep Friday night while remaining perfectly awake. I observed the following mechanisms for the sleeping and dreaming processes, which I will share below.
The body has two checkpoints to pass in order to enter sleep. One is physical, and one, mental. The physical checkpoint is well-known from the outside: sleep paralysis. However, from within, the body performs a physical check to ensure that it doesn't need to move. It gauges the brain's opinion of the body's comfort level as well as its likelihood to move in the near future, focusing especially on the head. When told that all is physically well, the body sends out nerve impulses to its regions to double-check. Any impulses it receives in response indicate a need for the muscles to move, and sleep cannot be entered. The impulse also wipes the slate clean of any smaller impulses that may be keeping the mind physically engaged.
The mental checkpoint determines that the brain doesn't need to think about anything for the time being. This includes the body's basic needs (e.g. safety, hunger, thirst, temperature, or pain) but also any patterns (e.g. a song stuck in your head) and general mental effort as well.
Then the cool part.
With the body and mind immobile, relative difference in inner ear sensation (as compared to normal inner ear sensations when the body is active and cross-referencing other information) create the perception of motion. The loss of proprioception due to paralysis deprives the inner ear of its last source of feedback from the outside world. For analogy, consider the active mind a person spinning, and the sleeping mind a person who has suddenly stopped. The echoes of signals we no longer receive create their own perceptions.* The mind reacts to this perception of motion by compensating (i.e. recognizing familiar types of motion and re-calculating its perceptions in that context), much as a sailor’s brain adjusts to the rocking of a boat. But, in undertaking this process on a perception series that has no simple basis, the brain creates further perceptions of motion—it cannot simplify the complex “phantom motions” and only adds to their complexity. Unlike a waking mind, the sleeping one cannot re-calibrate its impression of motion because it doesn't check with the other senses. A feedback-loop of motion and response ensues, which creates a frequency. Thoughts are stimulated in response to the complex motion and positional information passing through the brain. Thoughts are most responsive to spatial perceptions at this stage, and the mind can rapidly and efficiently modulate its thought patterns by modifying its spatial perceptions. As this spatial information triggers other types of senses within the brain, the unconscious mind slowly attains thought patterns very much like waking ones, without the addition of (most) real-world sensory input, and with one other key distinction, made below.
I did not enter REM sleep, to my knowledge.
I got the distinct impression from this experience that the conscious mind is essentially an instance of the unconscious one that is more constrained by stimuli which it deems important. The conscious mind is a state maintained by that brain system which determines importance and conducts ranking. Perhaps consciousness is just another, more active, version of what our brains always do. A state which is, like the others, delicate and only temporary.
*This implies a mechanism for sleep beyond the hormonal; simply moving around during the day may make it easier for us to sleep.