Should I stop work when I feel tired, or carry on because I’ve got goals?

Hello amazing people,
Here’s my question. I get really tired at around 9pm each evening.
Out of self love and self care should I stop working at that point?
Or should I push through and agree to be tired and to carry on anyway?
I get up early each day, around 5am, to get my own work done before I have to go to work.
What do you think my best strategy is?
I’d actually quite like to work on a bit longer than 9pm and get things ticked off my todo list. But am I doing the wrong thing by working through tiredness?
Is it normal to be tired at 9pm? quite curious about that. Do you think I just want to shut down because I’ve had enough and am starting to feel overwhelmed and like I can’t cope with being uncomfortable any longer so I need to go to bed?
I’d like to be able to motor on through, but if I do that, I quite often wake up around 11pm/11.30pm and then I am happy to stay up til 1am/2am, and then I’m tired the next day.
By 9pm I’m beyond doing strategic work, but even if I go and sit quietly to do some writing or some scholars work I will fall asleep.
Is this drama? Do I just say, ok I work until 9pm and not after that? Or, conversely, I work until 10pm even though I’m tired?
Would appreciate a little bit of direction.
Thanks so much.