Technique for determining sleeping state of user

A data processing apparatus that controls to display an image of a predetermined process on a body-mounted display device worn by a user, comprising:

• a position and attitude calculation unit that tracks a head, a face or a neck of the user, and calculates the position and the direction of the head, the face or the neck of the user;
• a display control unit that displays the image of the predetermined process in a virtual space of the display device such that a position and a direction of the predetermined image corresponds to the calculated position and direction of the head, the face or the neck of the user;
• a determining unit that determines that the user is in the sleeping state when a candidate state, in which at least either of the calculated position and direction of the head, the face or the neck of the user is shifted by greater than or equal to a predetermined set amount, continues for greater than or equal to a predetermined set period;
• and
• a process performing unit that performs a predetermined sleeping countermeasure process when it is determined that the user is in the sleeping state.