And I thought my DS was bad! You poor thing. It sounds to me that your DS has gotten himself into a nasty sleep pattern and is so overtired he can't relax nicely into sleep IYKWIM. I've not had a full night's sleep since I was about 7 months pregnant and I know how this feels myself...I am so tired but sometimes I just cannot go to sleep because I am so used to having tiny little sleeps.

Just to troubleshoot:

Do you have to get up to him ie can he ever settle himself back to sleep? No toys in the cot to distract him?

Is the room too light/too dark/too warm/too cold? Are his jarmies warm enough or alternatively is he too hot in what he is wearing? Is he kicking blankets off - if he is try a sleeping bag. I'm inclined to think he is not too cold because he would then be waking more frequently in the early hours of the morning and you say this is when he finally settles for a bit longer.

Is it noisy outside his room? Perhaps a lullaby CD playing softly in his room would help mask outside noises that might be disturbing him.

Is he having a nice big dinner before bed? ie he's definitely not hungry? Or alternatively, whatever he's eating for dinner, is it very sweet or something that might be difficult to digest and therefore disturbing his sleep?

Is he teething? (I know that some people say teething shouldn't affect sleep but pfft to that).

Do you have a bedtime routine that involves winding down time so he is nice and calm when you put him down?

Are you still breastfeeding? If so try cutting caffeine out of your diet - my DS was a different baby in 24 hours when I did this.

This might sound crazy but you could also try putting him to bed earlier than normal. I know that sounds strange but this actually worked with my DS and it didn't make him wake up earlier. We thought our DS was a baby that didn't need as much sleep as the average baby and when I first heard this suggestion I thought it was mad but now he goes to sleep around 6.00-6.30pm and he still wakes up at 6.00am regardless. We love it because he gets more sleep and we get our early evenings free!

I hesitate to suggest this last one because I'm sure it will be regarded as controversial - if all else fails try sedating him for just one night. My DS got into a really bad waking pattern after a tooth appeared and kept waking 4 to 6 times a night even though there was nothing wrong. I was beside myself and I was positive that DS was not getting enough sleep and because he was overtired it was exacerbating the problem. We gave DS a dose for just one night and he slept for 9 and a half hours straight which he has never done before (or since, but hey) and the following night we went back to our normal one to two brief night wakings. I had my MCHN's blessing, she commented that sometimes this is necessary to break the pattern they have gotten themselves into. I emphasise that I would only do this for just ONE night. I really didn't want to do this ("what! I'm not gonna drug my child" type of thing) but DH kind of made me because he said I needed the break and I was so tired I couldn't put up a fight and I'm so glad that we did because it did knock that nasty little pattern on the head (and I got a decent dose of sleep which I badly needed).

HTH.