By Steve Hodges, M.D.
Search “causes of bedwetting” and you may get the impression that nocturnal enuresis, as the condition is called, is a complex mystery.
Under the heading “Causes of bedwetting,” the American Academy of Pediatrics (AAP) offers a list of eight bullet points and states: “Although not all of the causes of bedwetting are fully understood, the following are some that are possible.”
In fact, virtually all bedwetting cases have one cause: constipation, fourth on the AAP’s list. Research proves this is the cause in most cases, and the mechanism is well understood. Most of the other “causes” posited by the AAP — such as deep sleep, stress, urine overproduction, and an underdeveloped bladder — are simply not supported by science and should be stricken from the list.
The problem with listing unproven or disproven theories — even if these theories are described only a “possible” — is that families and pediatricians waste time on therapies that don't work and miss out on treatments that actually do resolve bedwetting.
In this post I will discuss each of the eight bedwetting “causes” listed by the AAP, distinguishing between those that do belong on the list and those that don't.
#1) The AAP states: “Your child is a deep sleeper and does not awaken to the signal of a full bladder.”
This is a popular theory! Parents will tell me: “My son could sleep through a fire alarm.”
But deep sleep cannot cause bedwetting, because children with healthy bladders simply don’t need to pee overnight. (This is assuming normal fluid consumption; obviously, kids who chug a bottle of Gatorade before bed may need to wake up to pee.)
It’s not as if light sleepers are jolted awake by the urge to pee, whereas deep sleepers fail to notice the signal and thus drench their sheets. No child, whether a light sleeper or a heavy sleeper, should even have the urge to pee at 2 a.m.
Human beings typically don’t eat or drink overnight, so we don’t produce enough urine to need to pee. A healthy bladder has the capacity and stability to hold the urine we do produce.
When a person — child or adult — does feel the urge to pee overnight, it’s because the bladder has become overactive, spasming when it’s not full. (Exceptions include those late-night Gatorade-chugging people and older men with prostate enlargement, who don't empty their bladder well.)
In children, virtually all bladder overactivity is triggered by constipation: the poop-stuffed rectum presses against the bladder, shrinking bladder capacity and irritating the nerves that supply the bladder. In adults, bladder overactivity is typically caused by changes to bladder function that happen with age, though constipation can contribute.
Why don’t these kids wake up in time to avoid an accident?
For the same reason so many bedwetting children also have daytime accidents: an overactive bladder spasms too quickly for the child to react. It’s like a hiccup: You can’t prevent it. Even when they’re awake, many chronically constipated kids can’t sprint to the toilet fast enough to avoid an accident. So if a child is sleeping when the bladder spasms, what are the odds the child will wake up and dash to the toilet in time? Darned low!
The theory that deep sleep causes bedwetting conveniently overlooks the documented connection between bedwetting and daytime accidents. Most of my patients with daytime pee or poop accidents also wet the bed. A Swedish study found elementary-age kids who had daytime pee accidents were four times as likely to wet the bed as kids who did not have daytime accidents.
Also, a significant percentage of bedwetting children have daytime accidents. In a study of 16,000 children, about 15 percent of bedwetting boys ages 5 to 10 reported having daytime wetting, too; among tweens and teens, the overall bedwetting rate was lower, but 32 percent of the bedwetting kids in that age group also had daytime accidents.
Many doctors tell families that daytime and nighttime wetting are different conditions; in fact, they have the same cause.
Now, if you, yourself, have the urge to pee overnight, as many adults over 40 do, you may wonder why you wake up and make it to the toilet but your child doesn’t.
I don’t have a definitive answer. Some adults do wet the bed, but I suspect those able to avoid wet sheets experience a form of bladder overactivity that is less forceful and comes on slowly enough to allow for a wake-up and a trip to the toilet. Children, on the other hand, experience dynamic, abrupt bladder spasms.
One other point: While most folks assume bedwetting children sleep more deeply than other kids, there is actually some evidence kids who wet the bed sleep less soundly. A Chinese study summarized by its authors in a letter to the New England Journal of Medicine found bedwetting children got less REM sleep, probably because their bladders were going haywire all night. Every bedwetting child in this study was shown to have an overactive bladder.
Bottom line: Most kids are deep sleepers. Most kids don’t wet the bed. It doesn’t matter
if your child could slumber happily in a construction zone, because that can’t explain why her bladder spasms overnight.
#2) The AAP states: “Your child has not yet learned how to hold and empty urine well. (Communication between the brain and bladder may take time to develop.)”
Many parents are told their child’s “bladder hasn’t caught up with their brain” — that this communication is delayed. This was among the explanations offered to Betsy Rosso, the Virginia mom whose daughter, Zoe, was suspended from preschool for having “too many” accidents and featured in It’s No Accident, my first book. It’s an explanation many members of my Facebook support group have heard from their physicians — even when their child is age 7 or 10!
But it’s just not true. This explanation is based on a faulty understanding of how babies come to achieve dryness overnight.
There is a deeply held notion that when you’re a baby, you pee while asleep, and then, when your brain and bladder mature, you outgrow it. In reality, healthy mammals typically don’t pee while asleep. Your puppy doesn't do it, your kitten doesn't do it, and your newborn doesn't do it.
Research shows infants usually pee when aroused, if only slightly, from sleep. As a study in the European Journal of Pediatrics put it: “Most voids in infants occur when being awake or the infants awake immediately before voiding.” After peeing, they fall back into slumber. They do this multiple times overnight, because an infant’s bladder is small, and the filling/emptying cycle is what stimulates growth.
It takes a lot of brainpower to realize you have to pee. So even if babies and toddlers wanted to be dry at night and could venture out of their cribs, they rarely have the ability to get all the logistics taken care of.
However, once children sleep in a bed and are toilet trained during the day, they should have no problem staying dry overnight. At that point, the bladder is large enough to hold pee overnight. If a toilet trained child is wetting the bed, it’s a sign of an overactive bladder and/or low bladder capacity — not because the bladder is “underdeveloped” but because the clogged rectum is squishing it. (More on the “underdeveloped bladder” theory in #7.)
#3) The AAP states: “Your child's body makes too much urine at night.”
This “overproduction of urine” theory is the basis for treating bedwetting with DDVAP, a popular drug that tricks the kidney into making less urine at night. The theory is that in some children, the body doesn’t produce enough ADH, a hormone prompts the kidneys to release less water overnight, decreasing the amount of urine produced. So — the theory goes — these kids with a shortage of ADH generate too much urine, and by artificially restoring the hormone balance with medication, the child will stop cranking out too much urine.
Sounds plausible, except there’s no convincing evidence that bedwetting children underproduce ADH or overproduce urine. (The exception would be kids with medical condition such as diabetes insipidus, an extremely rare hormonal disorder that does cause an overproduction of urine overnight).
While some studies suggest bedwetting children produce more pee at night than kids who stay dry, plenty of others have found they produce normal amounts. If urine overproduction was the cause of bedwetting, DDVAP would be an excellent cure. But it’s not. About 30 percent of patients achieve dryness while taking this drug, but once kids stop taking it, 60 to 70 percent of the “successful” kids relapse.
Despite its dismal success rate, DDVAP is considered a “first line” treatment for bedwetting. I discuss this drug further in Bedwetting Medication Doesn’t Work — Here’s What Does.
If your doctor says your child is overproducing urine (and therefore needs DDVAP), don’t just accept this! Ask for proof, such as a test of your child’s ADH levels and plasma osmolality (a measure of the body's electrolyte-water balance). Chances are, your doctor will not order such a test (it will only come up normal!) and will offer an alternate theory.
Make sure you also ask for an abdominal X-ray, including a measure of rectal diameter. If your child’s rectum is wider than 3 cm, the child is constipated, and DDVAP is not going to attack the problem.
#4) The AAP states: “Your child is constipated. Full bowels can put pressure on the bladder and lead to problems with holding and emptying urine well.”
A rectum stretched by a hardened mass of stool can indeed encroach upon the bladder, sometimes to the point of flattening it. For many parents, this doesn’t hit home until they see the squished bladder on their child’s X-ray. That’s when they realize their child’s bladder can’t possibly hold enough urine overnight.
But the AAP doesn’t mention the other way constipation triggers bedwetting: by aggravating the nerves that feed the bladder. The bladder goes haywire, sensing it’s full when it’s actually not. Many children who wet the bed also experience urinary frequency, the constant need to pee, as well as urinary urgency, the desperate need to pee. Both of these conditions are caused by chronic constipation.
Plenty of evidence shows that constipation causes bedwetting. The definitive studies were conducted by Sean O’Regan, M.D., in Montreal in the 1980s. Dr. O’Regan used anorectal manometry, the gold standard for detecting constipation, to determine that bedwetting children’s rectums are severely stretched. The kids he tested had so little rectal tone that they couldn’t detect, in their bottoms, a balloon inflated to the size of a small tangerine.
In a study of children with daytime enuresis, my own published research found the rectal diameter of these kids to average about 6 cm, twice the diameter of the children in the study who did not have enuresis.
Oddly, while the AAP lists constipation among bedwetting causes, the academy does not include treatment for constipation as a suggested action to take. Why would you not treat the cause of a problem?
Under the heading “What you can do,” the AAP states: The problem usually disappears as children get older. If children reach school age and still have problems wetting the bed, it most likely means they have never developed nighttime bladder control."
In terms of what you, the parent, can “do,” that is not very helpful! The AAP seems to be saying: do nothing. What's more, the section is inaccurate, because the lack of “nighttime bladder control” is directly caused by the rectal clog. As for outgrowing bedwetting, yes, most kids do. But, according to the AAP, about 20 percent of 5-year-olds wet the bed — no small percentage — and you cannot assume any given child will outgrow bedwetting. As I explain here, children most likely to outgrow enuresis are those who wet the bed infrequently and who never have daytime accidents.
The AAP’s “What you can do” section suggests that concerned parents “talk with your child's doctor” and be prepared to be asked such questions as “Have there been any changes in your child's home life such as a new baby, divorce, or new house?” and “Does your child drink carbonated beverages, caffeine, citrus juices, or a lot of water before bed?"
Again, in terms of actions to take, none of that is helpful. The advice implies that drinking carbonated beverages or caffeine is causing the bedwetting. What is helpful — and necessary — is treating constipation aggressively, ideally through a regimen, such as the Modified O’Regan Protocol, that combines enemas and laxatives.
#5) The AAP states: “Your child has a minor illness, is overly tired, or is responding to changes or stresses going on at home.”
The site does not specify what “minor” illnesses would cause bedwetting, but I don’t know of any. I also know of no evidence that fatigue causes bedwetting, nor can I think of a plausible theory to explain how fatigue would cause bedwetting. Maybe this is a version of the “deep sleep” theory? Maybe, the AAP is implying, when kids are fatigued, they sleep more deeply and therefore are more prone to bedwetting? The academy does not explain (and that would make no sense, anyway!).
As for “stresses going on at home,” the evidence is highly suspect. The AAP doesn’t cite any studies to support that statement (or any of the others in this particular article), but the American Psychiatric Association (APA) makes the same point and does offer a citation worth looking at.
The most recent edition of APA’s Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), published 2013, states: “Enuresis can be triggered by separation from a parent, the birth of a sibling or family conflict.” The only study footnoted is a study published in an Indian medical journal, that makes this statement:
Birth of a sibling, parental separation, and family discord [are] some of the common emotional problems which lead to the persistence of enuretic behaviour.
But the Indian journal does not offer any citations to support this statement!
No doubt many bedwetting kids feel stress, but it’s the accidents that cause stress, not the other way around. Kids who wet the bed or have daytime accidents get teased and shamed for a condition they can’t control, and they often miss out on sleepovers and sleepaway camps. They have a lot to feel stressed about.
When I X-ray children whose bedwetting has been attributed to “stress,” these kids are invariably constipated — same as my other patients.
Prior to seeing me, many of patients were referred for psychological or behavioral therapy by their pediatrician or school, but easing stress never stopped the bedwetting.
If you want to read more about the theory that stress causes bedwetting, I suggest these
three blog posts:
#6) The AAP states: “There is a family history of bedwetting. Most children who wet the bed have at least one parent who had the same problem as a child.”
Research does show kids with parents who wet the bed are more likely to wet the bed themselves. But you can’t jump to the conclusion that bedwetting is hereditary. What’s passed on, I believe, is the propensity toward constipation and the propensity of a stuffed rectum to make the bladder spasm.
In other words, in some families, a rectum stretched to 5 cm in diameter — while abnormal — may have no effect on the bladder, whereas in another family, a rectum stretched to 3.5 cm — only slightly abnormal — may cause bladder hiccups. Some bladders are just more susceptible to the effects of constipation.
When you X-ray kids who wet the bed, virtually all of them are constipated, whether or not they have a family history of bedwetting. The problem with focusing on the heredity connection is that it prevents families from taking action. A parent will say, “Well, I wet the bed until I was 10, so I’m sure my son will come around.”
First off, you can’t possibly be sure your child will outgrow bedwetting. And why wait until 10 to take action when, with a treatment such as M.O.P., he could be dry at 4? In my experience, no one is served when a child spends six additional years in pull-ups. My bedwetting support group has numerous parents who wet the bed as children and regret waiting years for their own children to outgrow bedwetting.
#7.) The AAP states: “Your child's bladder is small or not developed enough to hold urine for a full night.”
The “underdeveloped bladder” theory is quite popular but also unfounded.
Loads of studies show the bladders of bedwetting children tend to have a smaller
capacity than the bladders of kids who are dry at night. But a study comparing the bladder capacity of bedwetting and dry children is worthless unless you X-ray the children for constipation. You can’t assume a child’s bladder capacity is compromised for developmental reasons.
When you look at X-ray after X-ray, you see quite clearly that these kids have small bladder capacity because the stool-stuffed rectum is squishing the bladder, making it impossible for the child to hold enough urine overnight.
#8) The AAP states: “Your child has an underlying medical problem.”
This is possible and worth mentioning, though rare. In more than a decade practicing, I’ve had only one patient whose bedwetting turned out to be caused by type 1 diabetes and one whose wetting was caused by diabetes insipidus.
“Laziness” Doesn’t Cause Bedwetting, Either
While I find the AAP’s list of 8 “possible” causes of bedwetting unhelpful, on the whole, I am grateful the academy does not list “laziness” or “attention seeking,” as possible causes, because I hear this a lot.
Some parents have been told by doctors, “He’s just trying to manipulate you” or “She’s lazy” or “It’s a control issue, and he’ll stop having accidents when he is ready.” (Those are exact quotes reported by parents in our Facebook support group.)
Given the amount of shame and blame heaped on these kids, you can be certain they are not seeking attention. If they are acting out, it’s likely because they lack control over their bladder and/or bowels, and that feels lousy.
The AAP Needs an Update
The AAP is a highly respected and popular source of information for parents, but in the case of bedwetting, the academy is steering parents wrong. I urge the AAP to revise its section on bedwetting, including its list of “causes” and the actions listed under “what you can do.”