Sleep...what is it good for?

I have given up trying to figure out Connor's sleep issues. We were doing really good for awhile, what happened? He naps really good during the day but every night is a mystery. He goes to bed around 8pm (earlier if he didn't have a good afternoon nap) and some nights he sleeps like an angel from 8pm - 7am like he did last night (thank god!) and other nights he wakes up crying and sceaming around Midnight. We try to ignore it but he never goes back to sleep so we (I) end up staying up for an hour getting him back to sleep!! I read an article the other day that said 'recent research has shown that sleep may also be disrupted in the few weeks before a major developmental leap, such as walking.' Yikes!!! I don't if I'm ready for this, I just got use to this crawling thing. I know it won't be long before he takes those first steps because all he wants to do these days is pull himself up on things. Ready or not, here he comes:)