I saw that another mom recommended giving cereal in a bottle at night -- please, please don't do this. If you choose to feed your baby solids at night, do it with a spoon. It is dangerous to feed a baby cereal via bottle. Also, many studies have shown that feeding a baby solids in hopes that they'll sleep through the night is more myth than reality. Onto more physiology...
Babies often wake up in the middle of the night due to bladder pressure (full bladder, need to pee). So there you are, awake too, and thinking that the crying is due to hunger (so you offer the breast, but he's not super interested) when in fact it's your baby wanting to pee. I was caught in this cycle with my daughter as well. Now stay with me here - before you laugh this off (which is what I totally did when I first heard about it, but now I know better since I've tried it and my baby loves it!) - you can give your baby a chance to pee in the toilet, and he might well fall back to sleep as soon as he's squeezing out the last drops of pee:
http://www.diaperfreebaby.org/pottypositions.htm?&MMN...
Or then he might actually want to nurse, but he'd be actively sucking and getting milk instead of just "hanging out" on your nipple. After we tried this approach (EC at night) with our daughter, the night nursing went WAY down (first waking 3-5 hours after going to sleep was pee only - did not want to nurse! - and 2nd waking like around 4 or 5am was a definite "want to nurse" followed by a big morning pee & poop).
Yeah, I know this is not a typical approach, but it really worked for us - if you are curious, want to learn more (and it's ok to be skeptical and to chuckle about how ridiculous it sounds at first, but seriously, if you try it, it will blow your mind! It's really cool, a great parenting tool!):
http://www.viviente.com/2005/10/how_to_do_parttime_pottyt...
http://www.diaperfreebaby.org/index.php?module=article&am...
http://www.diaperfreebaby.org/index.php?module=article&am...