Sleep - the thing itself is very resting and effortless (rather actionless). it is the process that leads to it that I find is interesting. The eyemuscles or rather the eyelid muscles - whatever is there of it- contracting like under a command from the brain (most probably) to cut off visual input. Other senses must have gotten the same command too for all of a sudden I cant seem to hear (or think, for that matter) clearly.
On the other hand, there is this 'keep alert' mechanism that acts against that which the muscle system is doing, all the while alerting the brain to keep awake while still grasping input (even when the visual input and audio input systems are functioning at half-throttle), and making a hodge-podge of input msges. Have you tried writing (actually with a pen and paper) during the fight-sleep process? I did, and i got an odd set of words mixed anyhow, like the Brocas area and Wernickes (of the brain cortex) have 'lost it' and are now throwing stuff anyway which. Same is the case when I multitask (or multithink) and have one thought running in mind while i work on something else, and i have sleep to fight off; the two thought trains gets cross-linked anyhow and create nonsense msgs.
Interesting experience, this fighting off sleep process. If the process is such, wonder what goes on in the 6-8 hours of the entire sleep cycle of a reluctant sleeper. It must be quite a circus in the brain during shuteye ,,sorry, shutsenses.