M.C.
I'm so sorry some people's responses have been less than helpful. My son was bedwetting until the age of six. I was changing the bed two and three times a night despite the fact that my son was wearing pullups. It was exhausting. I finally got a pee alarm that attached to his underpants. It vibrated and alarmed VERY loudly at the first sign of wetness. My son was such a deep sleeper that he just didn't wake up when he needed to pee. When we first got the alarm, we discovered that he was peeing six times a night while sleeping. At first the alarm wouldn't wake him up--we'd have to go in and remind him to go to the toilet, but after awhile, he would wake up on his own when the alarm went off. It took six months, but then my son no longer wet the bed at all.
Another trick I learned was to have my son wear his underwear under the pullups. The pullups stay so dry that kids don't feel wet in them, but the wet underwear is another cue to their brains to wake up and go to the bathroom.
Good luck. I hope this helps.