REM PLZ?

I understand that pregnancy can make you tired. I understand that pregnancy can make you frenetically wired to get the house in order. What I don't understand is how it can simultaneously make your mind race so badly that you feel you need to get up and do something at 3 am, and so tired that you nearly fall back asleep before you can open the bedroom door, so you say f*ck it and get back in bed. After using the restroom (AGAIN), of course.