Results from the October 2009 to October 2010 protected time cohort of interns will be compared with two comparison groups from the same institution and the same medical intensive care unit during the academic year June 2008 to June 2009. The first comparison group is interns working 30 hour shifts every 3rd night without any protected time and an average of 80 hours per week. The second comparison group is interns working a maximum shift length of 16 hours and an average of 60 hours per week.