I noticed that too, but assumed it is a natural part of the body being in stasis and no longer growing/developing. I definitely remember being most tired during

I noticed that too, but assumed it is a natural part of the body being in stasis and no longer growing/developing. I definitely remember being most tired during teenage years and other phases when the body was changing. You and others seem to imply that it has to be with increased stress, and maybe so, but I would like to see data on other cultures. Does someone who has been farming since age 17 have the same sleep patterns in middle age?