Eventually, the constituent atoms themselves perform a complete cycle (at the slowest rates) every ~7 years. Some substances (e.g. water) cycle much faster, obviously.

http://www.npr.org/templates/story/story.php?storyId=1189358...

Which tells us that sentient consciousness and identity is mostly about the continuity of a signal across only some cells (nerves), and mostly rides on top of standing waves supported by those special cellular processes, at frequencies of oscillation faster than the underlying polarized/ionic chemical processes.