Should you put your teenager in a night diaper?

It depends on the situation. If the child is night wetting, it is best to give him/her the choice (if he/she is mature enough) to choose protection. If its for daytime wetting, it's best to offer pull-ups or Goodnites so if they decide to go to the bathroom, they can.

Also speak to your doctor for guidance depending on what the medical (or mental, emotional) problem is. And take precautions like no water after 6PM. wake him/her up on regular hours during the night to go to the bathroom because often the bladder can be trained. But it depends on what the medical problem is. It's important the child feel safe but not too safe so they don't try to get back to normal.