This policy setting allows applications and services to prevent automatic sleep. If you enable this policy setting any application service or device driver prevents Windows from automatically transitioning to sleep after a period of user inactivity. If you disable or do not configure this policy setting applications services or drivers do not prevent Windows from automatically transitioning to sleep. Only user input is used to determine if Windows should automatically sleep.
HKEY_LOCAL_MACHINE -> Software -> Policies -> Microsoft -> Power -> PowerSettings -> A4B195F5-8225-47D8-8012-9D41369786E2 # ACSettingIndex
System -> Power Management -> Sleep Settings