(There may be also an explanation of why this is occurring in conventional medicine, too, but that’s not my field or expertise.)
You can think of the human body as being a sort of ‘liquid crystal’ conductor of electromagnetic energy. These electromagnetic impulses are one of the ways that the different parts of the body communicate with each other. They start off as thought impulses, convert into electromagnetic signals, and then zip-off to various areas to trigger off different physiological changes.
One signal will tell the body to produce more stress hormones, another signal will tell your brain you’re full after a good meal, and so on and so forth.
Now, according to Chinese Medicine the body has 14 main ‘energy pathways’ or meridians, that can be thought of as kind of super-highways for carrying these electromagnetic signals around the human body.
(BTW, a number of rigorous experiments have now been done in Western settings to prove the existence and veracity of energy meridians.)
Each energy meridian is associated with a different set of organs and / or physical functions
Each one of these 14 meridians is associated with a particular set of organs and / or physiological functions in the body. When a meridian gets blocked, weakened, or somehow unbalanced, sooner or later, that’s going to show up as some sort of emotional and / or physical issue or problem.
It’s similar to what happens when a log falls across a stream. For as long as the log is blocking the path, the water can’t flow along its regular route. You’re going to get flooding as the water builds up behind the log, but you’re also going to have things dry out and wither up ahead, because the stream is no longer reaching all that vegetation and watering it, the way it used to.
Remove the log, and things go back to normal – and it’s the same with energy meridians. Get rid of the problem or blockage, and the body will start to function properly again.
(There’s a lot more to say on this subject, and if you’re interested in learning more, I recommend picking up a copy of a book I wrote called: How your emotions are making you sick.)
How Your Emotions Are Making You Sick (Matronita Pocket Guides Book 3) - Kindle edition by Rivka Levy. Professional & Technical Kindle eBooks @ Amazon.com.
Bladder meridian and the nervous system
So now, we’re getting to the crux of your question: how is increased urination, wetting the bed etc, related to psychological trauma?
In a nutshell, the energy meridian that is associated with the nervous system is… the bladder meridian.
The diagram at the top of this post shows you the path the bladder meridian takes down the full length of the body.
When someone has experienced psychological trauma, they are often ‘living on their nerves’ – they feel jumpy, irritable, exhausted, panicked, scared, easily startled etc.
This is because psychological trauma can cause the body’s fight-flight-freeze response to get permanently switched on, causing the person to feel stressed-out, anxious and tense 24/7, which is a whole other part of the equation. This is directly connected to things like Post Traumatic Stress Disorder (PTSD).
If the nervous system is under strain, then the energy in the bladder meridian is also being weakened, blocked or disrupted in some way.
If this continues over time, or is particularly acute, it can and does result in the physical functioning of the bladder being affected, in some way.
That could easily result in the issues you described in your post, plus things like wetting the bed in children. It’s common knowledge that children wet the bed when they’ve been psychologically traumatized in some way: bullied, yelled at, threatened, scared, criticized etc.
It's also very common for children to be traumatised by watching the adults in their life fight, fall-out, threaten, get angry, breakdown, etc, even when it's nothing directly to do with the child.
How to fix the problem
At the body level, things like massage, acupuncture and acupressure can help you to rebalance the bladder meridian, and encourage the energy to start flowing properly again.
At the mind level, the psychological trauma has to be addressed and resolved. If it’s ongoing, take steps to remove yourself from the source of the trauma, if that’s at all possible. (If it’s an angry boss, that’s usually much easier than if the problem is a parent, spouse, or other close family member.)
If you can’t get away from the problem, then you have to identify things you can do to reduce the psychological impact of being in that stressful relationship or situation. Having firm boundaries really helps, as does understanding what’s really happening, and how negatively it’s impacting you, physically.
(Often, our physical issues show up because we’ve been ignoring our gut reactions about what’s really going on with some of the people around us, and how they are treating us and making us feel.)
At the soul level, any sort of meditation that focuses on things like self-compassion, forgiveness, and connecting to God in whatever way that feels comfortable can give you a very deep sense of being cared for and looked after, which can work wonders for taking down the deeper effects of psychological trauma.
Again, a number of scientific studies have now been done to prove the positive affects this type of meditation can have on traumatized individuals, but the best advice is to try it and see – because it really does work.)
TO SUM UP:
Bladder meridian is connected to the nervous system, and the nervous system gets taken out by psychological trauma. Take steps to remove and deal with the trauma (as much as possible), and strengthen the bladder meridian, and your issues should clear up.