M.C.
Hi -
I used a diaper at night for both my boys. My oldest boy used a diaper at night until one day he told me he thought he didn't need it anymore (I think he was close to 4 - I can't remember ;>) He never had a diaper again.
My second still uses a diaper at night (I won't even say how old he is). I believe he could now go without it but is too lazy to get up and go pee in the morning, so his diaper is huge when he gets up.
It's OK - it hard for them to hold it that long. They'll stop with the diaper eventually!
--M.