Hi J.,
Night time potty training is very difficult and the biggest thing you can do is try to be patient so it will relieve the stress he is already feeling about the bed wetting.
Cloth Night Time Training Pants are an excellent option. They will absorb the urine and keep clothing and bed dry. As he grows and becomes more aware of his body and functions at night, he will wake up and realize he needs to change them or get up and go to the bathroom.
Pull Up work for some children, but with recent research associating a link between male sterility and disposable diapers, I would hesitate to keep in Pull Ups all night long especially if you had him in disposables as a baby. The chemical reaction occurring raises the temperature in the diaper or training pants and keeps the testicals the same temperature as the body.
Of more serious concern are the toxic chemicals present in disposable diapers. Dioxin, which in various forms has been shown to cause cancer, birth defects, liver damage, and skin diseases, is a by-product of the paper-bleaching process used in manufacturing disposable diapers, and trace quantities may exist in the diapers themselves.
And what about the material that makes "superabsorbent" diapers so absorbent? If you've ever used disposable diapers, you've probably noticed beads of clear gel on your baby's genitals after a diaper change. Superabsorbent diapers contain sodium polyacrylate, which absorbs up to 100 times its weight in water. Sodium polyacrylate is the same substance that was removed from tampons in 1985 because of its link to toxic shock syndrome. No studies have been done on the long-term effects of this chemical being in contact with a baby's reproductive organs 24 hours a day for upwards of two years.
My point being, if this is going to be an on-going issue, you may want to use cloth training pants vs Pull Ups to protect him from the embarassment of bedwetting as well as his health.
He will grow out if it. If he tries to talk about it, just listen and wait for him to get everything out that he needs to say. A small revelation could make a huge difference!