User Activity Monitor : Monitoring Settings : Options : Pause while inactive
  
Pause while inactive
The Pause while inactive option gives the ability to suspend recording in the absence of user activity, which decreases the amount of monitoring data. When this option is enabled, recording is paused if the user does not press keys on the keyboard, does not move the mouse, nor clicks with it for some time. Recording resumes on any keystroke or mouse click/move. The value of this option specifies the maximum allowed inactivity time.
Double-click the option to view or change its value in the dialog box that appears:
Inactivity timeout - The maximum period of time (number of seconds) that a user’s session on a computer can be idle without user actions before the recording of this session is suspended. DeviceLock Service will automatically pause the recording of idle user sessions after the specified number of seconds.
To enable this option, set it to a non-zero value. The valid value is 3 or more seconds. To disable this option, set its value to 0. When this option is disabled, the DeviceLock Service continues recording even if there is no user activity.
 
Note: This option has no effect on the rules that include the triggering criterion Computer is idle for <number> seconds (see Setting up triggering criteria). Such rules do not suspend recording after the inactivity time specified by this option expires.