My son keep wetting himself at night and it's...

You have to look for the reason behind the bedwetting at night, it is better to know the reason rather than putting temporary solutions. You have to make some medical tests in order to figure out what the reason is, as he maybe suffers some Inflammations or other infections. If the tests results are good and clean, you will have to start making a timetable for the kid in order to be waken up to pee two or three times a night. We know that it is hard on you, but it will help the kid a lot. Then, if he wets his bed again, you will be knowing when is the exact time that he does it. Moreover, at the end of the day, the kid must not drink fluids or anything, so you can control him.

Be aware that all things that we have mentioned must be in a mutual agreement with the kid, as he should be accepting this situation to rectify himself. For instance, you can make a board with paper stars and every time he wakes up dry, he put a star, while if he wakes wet. After that, if he succeed in making all the week stars, you will have to buy him a little present.

Finally, there is a useful practice to make the kid do it, during the daylight, if he wants to go pee, let him lie on his back and raise his feet eight times