Baby wide awake at 3am?

This morning Blake woke around 3am (he has been sleeping through but occasionally wakes once in the night) , normally after a feed he goes back to bed without a fuss but this morning he just did not want to go back down. After many attempts and leaving him to cry for a bit I ended up getting him up, taking him into the lounge and letting him play with his toys as he was absolutely wide awake. He's just gone down for his morning nap now My question is last night after dinner he had a mini muffin that I baked for dessert which had a very small amount of sugar in it (plus carrot, banana, dates etc so pretty healthy) - would this be the cause? How long would it take to see the effects of sugar? I would have thought it would be quicker than that as he had dinner at 5pm and went to bed at 7pm with no problem. I know it might be just one of those things, Im just keen for it not to happen again!

I'd say it was just a body clock thing - unless he was too hot/cold and that made him think it was the morning?