My body is wired weird I can’t fall asleep before midnight even when I have to wake up early. My brain after 9pm starts to become active, but between 6pm and 8pm I get very drowsy and have to fight to keep my eyes open.
I am the exact same as you. And try as I might, I only sleep about 5-6 hours no matter how hard I try. I have been this way since junior high. I’m 61 now. Average bed time is 1:00 AM and I wake up about 6:00 AM. If I go to bed at 11 I’ll wake up around 4-4:30.