I am so sorry
I had similar, my parents smacked me a lot and although my dad never smacked me for not getting to sleep, he would threaten me that if I wasn't asleep in 10 minutes he'd come up and smack me and he always seemed so angry I was terrified.
I also wasn't allowed to get up to go to the toilet so I used to wee under my pillow instead.
When my dad figured that out, asked me what happened and I lied (because I knew I'd be in trouble) and said I spilled a glass of water, he chased me round the bedroom saying 'stop running, I'm not going to smack you' then when I stopped he smacked me . He repeated this a couple of times. Supposedly to teach me that it's not nice to lie.
I also shut off in my childhood and although I was very unhappy and isolated, I didn't show anything on the outside.
I'd been in foster care for my first year with multiple carers before they adopted me, so I think I probably shut off and relied on myself from then on anyway.
Took me many years to learn to open up.
In many other ways he was a great dad, he was affectionate and played with me, unlike my mum.
I would try again to talk to your parents and explain how it scared you and how traimatising it was. Even if they say they don't remember it, say you will remind them.
Easier said than done, I haven't confronted my parents about a lot of stuff because they also don't remember it and I don't want to upset them in their old age. My dad has generically apologised for how they were with me though, although it took him until he was elderly to do it, I think he reached a point where he knew we needed to have closure.