I would also be fascinated to learn this. Liked the idea for several years of gaining a PhD, but I just couldn't imagine taking three or more years out of my career at this point. The only vaguely-related anecdata I have is from my mother, in a completely different field, who was a nursery school teacher (kindergarten to our friends across the pond) with a strong emphasis on creative development, but only after retirement at 65 did she actually go to university and get herself a fine arts degree. Now she potters away in her little studio every day and will probably not be in any danger of losing her marbles.