A relative of mine is about 7 1/2 years old, and still has a problem wetting the bed at night only. His parents have tried EVERYTHING, including the liner you put in the (underwear) and right when it feels wet a LOUD bell goes off (I heard this go off and my sister can hear it 2 rooms down the hall. That didnt work because he didn't hear it! They took him to his DR, who said he could still outgrow it. He didn't dismiss it for that, but said to keep an eye on it.
One of the big problems is that he sleeps so soundly that it is even hard to get him up in the middle of the night to go to the bathroom when someone wakes him up (and even then he is wet 3-4 hours after going to sleep). And in the morning he has no recollection of getting up in the middle of the night.
They know 100% that it really something he can't control and is just happening because of the many different ways they have helped him, and lately they said as an incentive if he could go one month withough wetting the bed they'd get him this big very expensive Lego set that he really wants badly. The incentive is really there, and has been for awhile, and he still wets the bed. It is starting to get embarassing for him because he is just that age where he doesn't want to wear a pull-up, or underwear with the consequence of wetting the bed in the middle of the night.
They've tried many things that I dont remember what they had told me, but does anyone have any suggestions of what to do to help him?