The day before he died, my father, who over the course of several years had suffered a steadily decreasing awareness of and interest in his and others’ lives, finally appearing to no longer have an inner life, suddenly, briefly and inexplicably returned to the world. I described this here.
I’ve found out two things since then. There are many anecdotal reports about this phenomena, and there is next to no medical research, explanations, or theories about how this happens.
I can’t really imagine how researching an unexpected event could proceed. I suppose there could be people on call, like transplant teams, but then what? Would the dying person who has returned one last time to engage with the world be rushed into an MRI and subject to various medical tests? Perhaps some would agree to this, if they believed that by so doing others could be spared their suffering, and if they were asked before they lost the mental capacity to make that decision: you can see the difficulties.
I finally found one study about this subject: “Terminal Lucidity in Patients With Chronic Schizophrenia and Dementia: A Survey of the Literature” by Michael Nahm and Bruce Greyson, published in The Journal of Nervous and Mental Disease (December 2009, pp 942-944).