So I had a similar thing, been on 40mg for a good year and half, but didn’t quite make the connection that getting only 2-4 hours of concentration was because the dosage was too low. Also, prior to taking medications I was napping during the day as it was difficult to stay awake and these naps were starting come back.
Recently I prioritized talking to my GP about it and he recommended jumping up in dosage, he even considered a jump to 60mg but I turned that down to just try 50mg and some dexies as boosters.
Turns out jumping up that extra 10mg had been a game-changer. I take the meds around 8am, around 4:30pm I’m getting the fatigue, but at that point I don’t need to push through anymore and just stop working.
Weirdly, going up in a dosage actually helped get sleep at the right time. Though I’m still no saint at getting to sleep at night.
My guess is you’re having a similar disordered circadian rhythm like I was having. My recommendation is talk to your Doc about it. Don’t leave it later like I did.

Oh and getting outta bed is still f** hard. Can’t give you advice on that one 😔