Apple TV waking up in the middle of the night.
My grandfather’s Apple TV sometimes wakes up in the middle of the night and plays a screensaver.
Apple TV 4K (3rd generation)
Unless one disconnects it from ac powe,r it will act the role of homekit hub and airplay 2 receiver, then it's sort of always running even if it does not display stuff on the tv, which means if it crash because of a software or hardware issue, it will reboot and that will result in what you describe.