Diagnosis
This is typically caused by an automatic software update check or a malfunction in the Android TV's Quick Start feature. The TV wakes from standby to check for updates or refresh app data.
How to Fix It
Disable automatic updates. Go to Settings > System > About > Software update. Set Automatically check for update to Off. Next, disable Quick Start. Go to Settings > System > Power & Energy > Quick Start. Set it to Off. The TV will take longer to boot from a cold state but will not wake autonomously.
If That Didn't Work
An external device connected via HDMI-CEC (Bravia Sync) may be sending a wake-up signal. Turn off CEC on all connected devices individually (e.g., cable box, game console). On the TV, go to Settings > Channels & Inputs > External Inputs > Bravia Sync settings. Set Device auto power off to Off. Set TV auto power on to Off.
Heads Up
If the TV is connected to a smart home system like Google Home, check for routines or commands that might be turning it on. Disable the link in the Google Home app as a test.