Many doctors believe that a small-capacity bladder causes bedwetting, but this isn’t entirely true. In fact, the answer is much more complex.
The logic behind this assumption is that bedwetters have smaller capacity bladders than non-bedwetters, and accordingly they have difficulty storing the accumulated urine through the entire night.
Let’s clarify this issue. We distinguish between two types of bladder capacity:
Functional bladder capacity—the bladder’s volume initiates contractions in the filled bladder, which consequently sends a signal to the brain.
Structural bladder capacity—bladder volume is similar among bedwetters and non-bedwetters.
Based on this theory, when the child learns to restrain himself for longer periods of time during the day, his functional bladder capacity is also increased until he manages to stay dry at night. It is believed, therefore, that special exercises to increase bladder capacity will assist in the learning process.
A bladder with a small capacity no doubt makes the restraint process more difficult, but the unanswered question is why do those children with such a bladder not wake as a result of accompanying pressure?
Many of these children wake a few times every night to empty their bladder in the bathroom.
We can certainly conclude that a bladder with a small capacity doesn’t cause bedwetting, but it can be a contributing factor.