Sorry I didn't reply earlier - I had a visitors for a while.
From what I read in medical literature, adult enuresis (bet wetting) from a previous injury can mean that the nerve endings that would normally tell you that your bladder is full and alert you during your sleep is not functioning properly. This can be a result of scar tissue. Scar tissue can grow, so, if this is getting worse, this is a concern. If the pattern has not changed, then the scar tissue may have not grown.
It doesn't happen during the day because the signals you are getting that you have to go to the bathroom is easier to feel when you are awake and more conscious to feel the signals. When you are sleeping, you are not feeling the signals like you would when you are awake. You may not be getting strong enough signals.
Some studies say that sleep apnea can trigger this, so if you have a problem with sleep apnea, given the previous trauma and the diminished signals you may be having, this is why enuresis occurs. Read this article (click below):http://ezinearticles.com/?The-Root-Causes-of-Adult-Enuresis&id=117877
Here is a study that links daytime continence and nighttime incontinence to urinary obstruction (click below):
So you see, this is something that warrants further investigation. One of these reports said that enuresis can lead to eventual daytime incontinence in men because it can be progressive.
There are some medications that you may want to speak to your doctor about, or using an alarm to train you to get up at certain times. Read this article (click below):http://www.myhealthsense.com/response_051121-bedWetting.htm
So there are some things that can be tried to see if it helps.
Hope this information is helpful to you.