I'm up at night peeing too, usually around that 3:30 mark. I keep my eyes closed the whole time, turn on no lights and go right back into bed.
In the past I've had issues with sleeping, and know that once its a problem its really hard to get past it, because you're now thinking about it! And I totally sympathize with the daytime sleeping thing. It hasn't been until this pregnancy that I have figured out the meaning of the word nap.
Some suggestions...try going to sleep at a different time..earlier or later and see if that helps. Don't drink any liquids past a certain time of night and pee two or three times before going to bed to make sure your bladder is empty. If you drink any caffeine try taking it out of your diet. Don't flush the toilet. Try some sort of meditation/visualization when you do go back to bed and try not to think of your ds waking up at all...stress is no good. Turn off your brain and do not think of anything you need to do the next day. Most of all..try not to think about the lack of sleep at all!
Hopefully this helps!