I spent over twenty years not sleeping. And it took me nearly all of those twenty years to fathom it out.
Forget what people tell you what you should be doing as we are all individuals and are all different.
I use to go for two or three days without sleep. It was a bit well known on the forum that I could run at 2.30 am , do a twelve hour shift and keep going. I still can. But I finally solved my problem with sleep.

Nothing to do with milk, Bert, windows , green tea or that kind of thing.
Be honest with yourselves and you will find why you cannot sleep.
Right I'm off to bed

Oh when I was assessed by the medical health team before having treatment they calculated that I had gone 15 years on 4.3 hrs a night. That's not uncommon either.
So I wouldn't worry about a little bit after Xmas, that's normal.

Ps caffeine is bollox. I've had 2 x caramel lattes today and 3 normal coffees. It won't affect my seven hours tonight.