I can concentrate pretty intensely for multiple hours on anything that has my interest and I'll be lucky if I can force my brain to focus on anything I don't want to do for longer than a second.
ADHD or autism? ;D
I used to have the same problem at night, where I would just think so much. Once I really started writing decently, it all went away and I sleep like a drunken baby.
Probably both x_x
both too lazy and don't have time to get an official diagnosis, current job somewhat knows about it but it hasn't been a problem, they just let me do my haha quirky little hacks like keeping my watch on so I have a prayer of figuring out which way left and right is (hilarity is I have a tattoo on my left arm that I know is on my left arm but it still doesn't always grok) and giving the kids coloured toys because I can't wrap my head around American warmup but colour patterns are easy
LoL! As far as I can tell that's a common problem. During the day your average adult is usually incredibly busy working, doing chores, running errands, caring for family etc etc etc that you don't have time to process anything that you need to process until all you want to do is go to sleep at the end of a busy day but seeing as that's literally the only time you have, that's when the brain goes nope first we need to process absolutely everything XD
I occasionally wonder if that might also be part of the reason why a lot of people do the revenge bedtime procrastination thing as well, I know people who will be on their phones til they can't physically keep their eyes open anymore because they're actively refusing to process things