Funny isn't it, my son wakes up when i open the bedroom door to go to work, but the TV wont wake him.FWiW with regards to volume, i've not turned the tv down when the kids are in bed and they've never woken up because its too loud, even when watching an action film. I do remember them waking up with creaky floorboards when they were young but fortunately they outgrew that.
Best thing i got was smart bulbs great when your putting him to bed and have no free hands, "Alexa George light on", have a Nest Protect on the landing which has a light with motion sensor and that's been a godsend as well, its just bright enough to see where your going.
). A long time to go yet but I can imagine it comes around faster than you think, plus, with buying a house it'll fly-by.

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