You don't sleep in one smooth homogeneous states but in wave like cycles. In between two cycles is when you might wake up in the middle of the night; not in a bad way, but just regaining consciousness way. Most of these waking states are forgotten because they're so short and sandwiched between slumber.
Just an hour ago, I laid in awake in the pitch black bed room for about ten minutes thinking of the day ahead and felt not the passionate energy of someone starting something new, but the tranquil pleasure of continuing something ongoing. And then I said why the hell not, let's just get up and get at it now.
Ethics and habits make us who we are. This site is filled with tidbits from Atomic Habits and The Power of Habit so there's a good chance you know this. But one ethic and habit I treasure is not allowing myself to look at the phone while in bed. I sometimes do check the time, but other than that i don't scroll through aimlessly treating my phone like a digital-social fridge. So just an hour ago, I didn't even check the time. I assumed it was relatively close to my wake up time. But it turned out it wasn't even four yet.
The old Abe would've been up at 3:40 not because he was excited to tackle the day. The old Abe would've been up at 3:40 because he was not satisfied with the day and had stayed up late thinking that just extending it would somehow make it better.