A method and apparatus for utilizing an inertial measurement unit and one or more additional sensors on a head mounted display is provided. In an embodiment, a head mounted display system sends inertial measurement unit data and head mounted display removal data to a tracking computing device. The tracking computing device identifies a time of removal of the head mounted display from the head of the user and stores a portion of the inertial measurement unit data corresponding to the time of removal of the head mounted display from the head of the user. Based on the stored portion of the inertial measurement unit data, the tracking computing device determines a state of the user of the head mounted display system at the time of removal.