When does the human spirit decide that it can let go of the body? Does it recognize this point consciously or subconsciously, cognitively or spiritually?
When someone is dying slowly, as in they know they have a disease or condition that will take their life in some short, definite amount of time, it is possible to watch the digression of health all the way to the point of the cessation of life. As happens every day, things get worse, more painful, closer to death, and finally the person crosses over into something else. But in that continuum, there is a point of change that is indiscernible. Anyone who has ever risen early enough to watch specifically for the sunrise knows this quandary. When are you looking at a rather light night sky, and when are you suddenly looking at a dark morning sky. At some moment there is a transition that we can not truly label, but it must exist. Perhaps a state where both exist at once, night and morning, life and death, veiled and unveiled.
In the case of slow deterioration there comes a point where the will and ability to draw one breath is not followed by the same will and ability. The next breath is never drawn. What occurred in those 4 or 6 seconds between the final breath and the first non-breath. The cancer did not grow suddenly worse, the lungs did not suddenly have more fluid, emphysema or leukemia or ALS did not progress at an incredible rate for that short moment in time.
So what happened? Friends and family often say that they finally got tired of hanging on. If that were the case, it would make the decision to die a cognitive one, something within our direct control and decision. If death were that much in our control, those with terminal diseases coupled with chronic pain would simply "choose" to die and do so without external aides. Contrarily, on extreme ends some individuals survive the impossible by an apparent "sheer force of will", while others will die of grief. Both are internally driven, yet neither can completely control what is happening. There is some aspect of internal choice and will at play, but it can not encompass the entirety of this
What is the final straw that allows someone to go past that threshold of what holds us onto life?