It looks like I owe an apology to my cat, because it apparently IS possible for an Apple TV to wake up and turn on the TV all by itself.
Some owners of the fourth-generation Apple TV are complaining that the device is spontaneously waking up itself and/or connected TVs, an inconvenience that could burn unnecessary electricity and could potentially cause screen burn-in for people with plasma sets.
A number of Apple TV owners have complained of this issue in Apple’s support forums, and this reporter has also experienced waking up in the middle of the night and finding my television on, displaying an Apple TV screensaver. (I blamed it on the cat playing with the Siri Remote while it lay on the coffee table. Sorry Dino!)
Users say the Apple TV may take it upon itself to wake up after being put to sleep, sometimes as quickly as one minute later – though usually longer, and at the same time turning on the attached HDTV display. This can occur with HDMI-CEC-equipped televisions.
At this time, the exact cause is uncertain, with owners blaming everything from Bluetooth issues to AirPlay flaws. Some users report success in closing all of the open apps on the device before putting it to sleep, or even restarting their units. For those whose only concern is keeping their television’s display turned off, they can disable HDMI-CEC in the unit’s settings.
The issue likely lies in a system software bug, which hopefully Apple will fix with a future update. However, we haven’t seen any reports of any such patch in the tvOS 9.2 beta that was released earlier this week.