What's going on?

[~me~]

It sounds like a wonder week. Have you read or heard of the book? It helps explain your little one's behaviour at certain development stages.
At 1yr old he is probably 'practising' and finding it hard to switch off. So when he wakes in the night, he wants to move or roll around or crawl or walk (whichever he has learnt recently).
It something that passes It drives you batty, it will get better

[MummaSue]

DD is very active in her sleep just now and we are going through wonder week 37 at the moment!

Apparently they are still processing all the physical stuff they do in the day time, when they are sleeping.