9 month old tosses and turns after 4am

[Majidmania]

My baby is a good sleeping, he’s asleep by 8pm and knocked out by 4am.

Then bizarrely he tosses and turns until 7am. Like literally moves his head from left to right every minute. But he’s asleep or half awake I don’t know. I know he does this because this is when I pick him up to co sleep as he wakes up crying at 4am.

Why does he keep tossing and turning and always at the same time every night?

Is it when the light starts to come into his room? Could it just be lightening his sleep a nit too much, and then he struggles to get back?
I've also been told they can get into habits, or waking at 4, because they know they'll get a cuddle at 4. Not sure how much I believe this as they can't tell time! But it could be part habit?

There’s definitely something about 4am. If our 7.5 month old wakes earlier than 4am, she’ll have a sip of water and go back to sleep (after a bit of teddy basketball and cot gymnastics) till maybe 6am. If she wakes at or after 4am it’s GAME OVER and a massive battle to feet her back down.

I wouldn’t mind if I could just bring her in with us and she’d actually co SLEEP instead of co giggle/pull hair/do sit ups/blow raspberries 😩

Exactly the same thing happening with our 5 month old. Goes down like a dream at 7pm, maybe need one little rock in the moses in the early hours but from 4am her head shakes left to right (we call it 'Stevie Wandering' if I left her she would wake up but if I pull her into bed I can usually keep her asleep until 7.

Dont want to build bad habits but have no will power to test how long she will stay asleep on her own at 4am