Bed wetting.
I knew a very bright 16-year old boy who wet his bed. He was a student in college at the time. He had suffered from the problem for many years. Finally, his parents took him to a urologist. He was diagnosed with a low-grade, chronic bladder infection. The urologist prescribed a urinary tract antibotic. The bed-wetting vanished.
The moral of the story: Find out what is wrong before trying to fix it.