The Child Who Wets the Bed in Their Sleep
The short answer
Bedwetting is not a habit. The hormone that reduces urine at night, the amount the bladder holds at night, and the power to wake from sleep at the signal that the bladder is full — which of these three is not yet grown in is what makes it look different from child to child.
Contents
"During the day there is nothing wrong; it is only at night. I have scolded and I have cut back the water, and it is still the same."
When a mother says this, her face is usually heavy. The child's face is heavier.
So before I examine anything, I say this first. This is neither a habit nor laziness.
Holding Urine Through the Night Takes Three Things
I wondered why a child who is fine during the day should have trouble only at night. There is a reason. Holding urine while asleep takes three things falling into place together.
First, less urine has to be made at night. The body has a hormone that, once night comes, makes the kidneys throw away less water. This hormone has to rise at night for the amount of urine made during sleep to fall.
Second, the bladder has to be able to hold that amount. The volume a bladder holds at night is different from during the day. If that volume is still small, it overflows even when the amount made is small.
Third, the signal that it is full has to wake the child. When the bladder fills, a signal goes up. That signal has to carry strongly enough to break sleep for the child to get up and go to the toilet.
If even one of the three is not yet grown in, the bedding gets wet. And these three come to completion at slightly different times as a child grows.
This Is Why Scolding Does Not Work
None of the three is something a child can bring about by making up their mind. How much the hormone rises at night, how much the bladder holds, whether the signal is strong enough to break sleep — not one of them can be governed by will.
The part about not waking is especially easy to misread. These children are on the side of not rousing well from sleep, so to a parent's eye they look like unusually deep sleepers. That is where "he won't get up even when I wake him" comes from, and it sometimes carries on into being called lazy. What is actually happening is that the signal is not strong enough to break sleep.
When scolded, the child comes to dread going to bed at all. As the worry grows, sleep grows light, and as sleep grows light the rhythm of the night is disturbed further. Scolding is not only unhelpful; it runs in the opposite direction.
I Look at Which of the Three It Is
Because where I look changes with which of them is caught, I ask about several things separately.
Whether the amount at night is a lot or a little, around what hour of the early morning, how many times in one night, whether the child needs to go often during the day as well, whether they hold it and then run in a hurry, how much they drink in the evening, whether their sleep is deep or light, and whether they snore — I look at these together.
For a child who needs to go often or urgently during the day as well, the bladder side of the story is the larger one. For a child who has trouble only at night and in large amounts, the story of the night's rhythm is the larger one. If sleep is unusually deep and there is snoring, I look at breathing during sleep as well.
I think this is also why this medicine has long looked at children separately. A child's body is not a scaled-down adult's, so when one thing wavers, several places waver with it. In a child whose night rhythm has not yet settled into place, sleep and eating often waver along with it. (A Child's Body Is Not a Scaled-Down Adult's)
What You Can Do at Home
A few things help at home.
Cut back the water a little in the evening, but let the child drink enough during the day. Going without during the day and then drinking it all in the evening is worse. Have them go to the toilet once before bed, and keep the bed a place free of worry.
Do not scold the wet nights; welcome the dry ones. This difference is larger than you would think.
When It Is Better to See a Doctor First
If dry nights ran on for several months or more and then it started again, if the child wets their clothes during the day as well, if it hurts when they pass urine, if they are unusually thirsty and passing a lot of urine with it, or if severe constipation is layered on top — then checking comes first. Another story may be mixed in.
We began with the words that you have scolded and cut back the water.
My answer is this. There is simply something that has not grown in yet. Reducing urine at night, holding it, waking at the signal — these three come to completion each at its own pace.
So I do not leave this as the child's fault. Looking at which of the three is not yet there, and tending to the conditions on that side, does more for the child and for the mother alike.
References
- A pediatric nephrology review setting out bedwetting along three lines — night urine volume, the bladder, and arousal — Pediatric Nephrology, 2011
- The waking response to the signal that the bladder is full does not readily occur — a pediatric sleep study — Journal of Clinical Sleep Medicine, 2017
- Scolding does not help — a pediatric practice guideline — Paediatrics & Child Health, 2023
Written by Dr. Heo Ji-young (PhD in Korean Medicine Pathology, Kyung Hee University · former Research Professor of Herbology, Kyung Hee University)
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