hi, yes there is more downs than ups in the ph.d but do not worry cause you are not the only one feeling this way. the other day I google"why doing a ph.d" then I found really interesting research paper describing the negative effects of ph.d stuy on student health. the papaer title is "Pursuit of the Ph.D.: Is it good for your health?"
Paper presented at the 4th International Multidisciplinary Qualitative Health Research Conference Vancouver, British Columbia, Canada, February 19-21, 1998.© 1998
it is free online you can google and see other people desribe there experience as well.