Here is a link to the 2016-2017 AZ hunting regulations
https://portal.azgfd.stagingaz.gov/PortalImages/files/regs/mainregs.pdf
See page 82 in the hunt regulations, "GENERAL (DAYLONG SHOOTING HOURS) PREDATORY & FUR-BEARING MAMMALS"
Night hunting is allowed for "coyotes only" in the following game management units from Dec 1, 2016 to May 31, 2017:
4A, 4B (north of Interstate 40), 5A, 5B, 8, 10, 12A,
12B, 13A, 13B, 15A, 15B, 15C, 15D, 16A, 17A, 17B, 18A,
18B, 19A, 19B, 20A, 31, 32, 42, and 44A
What's the reason not all of AZ is open to night hunting:
I'm not sure. My guess is that some southern units have big game hunts in progress from Dec through Feb. for Coues deer and javelina. Possibly conflicts with the Border Patrol near the Mexico border at night. Region 1 and Region 2 are in the higher elevations where access is closed anyway due to snow depth.