Give baby a "Dream Feed".
Similar to what I_did_dab says, but you don't wake them up. Pick the baby up (still asleep) at about 10pm and bung a bottle in her/his mouth. They drink it, still asleep, then you put them down. The disturbance is just enought to reset the sleep pattern and the full belly should get you through til 5 or 6, and it should get better from there with time.
Worked for my two, and you can keep going up to about 18 months – by which time yer kid'll be sleeping as it should. Don't worry about people saying it's a step backwards, it's whatever works FOR YOU, and I'm telling you, the best way to be the best parent you can be is to make sure you're getting the rest you need.
Gina Ford's a pretty good reference, but there are a number of other good books giving other perspectives. If you read a number of different methods you can work out the combination of methods that works best for you, rather than just blindly implementing. The Baby Whisperer (Tracy Hogg) books give an interesting perspective too.
Sweet dreams!