“William James wrote, “All my life I have been struck by the accuracy with which I will wake at the same exact minute night after night and morning after morning.” Most likely it’s the work of the circadian clocks, which, embedded in the DNA of my every cell, regulate my physiology over a twenty-four-hour period. At 4:27 a.m., I’m most aware of being at the service of something; there is a machine in me, or I am a ghost in it.

And, once the ghost gets thinking, there is much to think about—most of all, how little time I have in which to do all the things I’m thinking about and how behind I am.”

http://www.newyorker.com/magazine/2016/12/19/the-secret-life-of-time