Insomnia/poor sleep in a 3.5 year old

[Allyinoz]

My son is 4 in November, we have a new baby due October. Lately he has gone from being a good sleeper, 12 hours, to waking regularly around 1am for up to 4 hours.
Sometimes it is monsters, dinosaurs etc we have talked to him about these and tried many different tactics, sleeping in my bed (when all esle fails). Consequences, calming, night lights, singing, books, allaying his fears in the day. Talking his worries through. However lately there doesn't seem to be a cause just a very long night. I am already very tired and this is driving me up the wall.

He realises what is going on, doesn't seem to be able to go to sleep again and starts on a long list of things that he needs, drinks, more blankets etc...

I don't like leaving him to cry as he is extremely persistent child and can go for hours. Any ideas??

We had this but not any more. tried loads of things but one thing that did help a lot was going into his room and sleeping there (we had a yoga mat which seemed the handiest thing to store in there). I know it sounds a bit drastic, especially if you are pregnant, but it just avoids all that getting into conversation in the middle of the night and at least you are lying down! he could still be awake for ages like this but at least the atmosphere was conducive to actually going to sleep - quiet, reassuring etc. Good luck, it will pass.