It was same case with me, I too was go to sleep pretty late, when I tried P3 for the first time. Really great game.
If you can, and still didn´t play Persona 4, try it. I have only one thing in mind, that I didn´t like. And it is, that P4 is too same, as P3. Nearly all mechanic that were in P3 are in P4 too, altought upgraded. But still, P4 is too grat, and I will say even better than P3.








