Kate, at least you can say you have a good night sleeper. That must help with the sanity a bit. I think what worked for DS1 was wrapping him during the day for his sleeps. I know this does not work for everyone, but it worked for us. We had him in sleeping bags, but i got a huge sheet of muslin and wrapped him (arms out) and gave him his Ookie and patted/rocked/feed/cajoled him off to sleep. It seemed to help with that startle thing that babies (and adults!) have.
And being prepared to sleep with him - even if that meant lying down during the day with him. Power naps were the big problem. If he caught just a tiny cat-nap instead of a sleep, then it seemed to recharge the batteries for another 3 hours or so.

ETA - and Enya on repeat on a little cd player in his room.