Toilet Training

I know, I know you are wondering why I am discussing such a topic when I have school age boys who are both toilet trained...?
Well they are both daytime trained but we still have issues with night time.
I am one who has never been worried about night time training, I know it is a process we have to go through but I also know that their body has to have the ability to wake them in order for them to know they need to go when a sleep.
If their body doesn't wake them then how can you growl and scream at them for yet another accident or even how can you run a rewards chart for every morning they are dry and then punish them for the mornings they are not??

Ben was close to 6 when he was stopped wearing pullups, Grandma noticed that when staying with her he would immediately use the toilet when waking and his pullup was dry. So off came the pull up and no worries since. We have had the odd accident but nothing to write home about. In fact it was an amazing feeling when he appeared at the bottom of the stairs one night over a year ago and annouced he needed to wee.
I sat there thinking "thank you, at least now he wakes when needing to go, problem solved"

Alex on the other hand, well he is the child that announced when 3 that he was no longer wearing nappies during the day, 2 weeks later he was dry (took us 5 months with Ben). He would also have loved to have gone nappyless at night but I wasn't ready for that just then.
Several times he announced that he was no longer wearing pullups at night and several times after trying for 5 nights and having been wet for 3 of them then we have said no, we will wait a little longer.
He was always wet at different times as well, sometimes I would find him in a wet bed at 10.30pm sound asleep, very difficult to night train someone who manages to sleep through it all.
Othertimes it would be 3am or 5am that he would wake us to say he was wet.

About 2 months ago we noticed that just about every morning his pullup was dry, so we instigated a no pull up rule and away we went. I expected a few accidents along the way but every 5-6 days is hard work.
Again it is always at different times, 11pm, 3am, 4am, 5.30am.
I am not sure if he wakes because he is wetting or if he is waking because he is wet?

We have tried limiting his fluid intake after a certain time.
We ensure he wees prior to going to bed.
But so far we can find no rhyme or reason for this continual wetting that seems to be happening apart from the fact he is on school holidays and getting a lot of fresh air and obviously is just so tired each night that he is sleeping so soundly!

However we are now at the stage where we have to perserve and just go with it.
The lucky part of it all at present is that we are in the middle of summer and getting the washing done each time is easy.

If you have any suggestions or tips then we would love to hear them.....?