What Causes Nighttime Incontinence? (page 2)
Parents or guardians of children who experience bedwetting at night or accidents during the day should treat this problem with understanding and patience. This loss of urinary control is called urinary incontinence or just incontinence. Although it affects many young people, it usually disappears naturally over time, which suggests that incontinence, for some people, may be a normal part of growing up. Incontinence at the normal age of toilet training may cause great distress. Daytime or nighttime incontinence can be embarrassing. It is important to understand that many children experience occasional incontinence and that treatment is available for most children who have difficulty controlling their bladders.
How does the urinary system work?
Urination, or voiding, is a complex activity. The bladder is a balloon-like organ that lies in the lowest part of the abdomen. The bladder stores urine, then releases it through the urethra, the canal that carries urine to the outside of the body. Controlling this activity involves nerves, muscles, the spinal cord, and the brain.
The bladder is composed of two types of muscles: the detrusor, a muscular sac that stores urine and squeezes to empty; and the sphincter, a circular group of muscles at the bottom or neck of the bladder that automatically stay contracted to hold the urine in and automatically relax when the detrusor contracts to let the urine into the urethra. A third group of muscles below the bladder (pelvic floor muscles) can contract to keep urine back.
A baby’s bladder fills to a set point, then automatically contracts and empties. As the child gets older, the nervous system matures. The child’s brain begins to get messages from the filling bladder and begins to send messages to the bladder to keep it from automatically emptying until the child decides it is the time and place to void.
Incontinence happens less often after age 5: About 10 percent of 5-year-olds, 5 percent of 10-year-olds, and 1 percent of 18-year-olds experience episodes of incontinence. It is twice as common in boys as in girls.
Failures in this control mechanism result in incontinence. Reasons for this failure range from simple to complex.
What causes nighttime incontinence?
After age 5, wetting at night—often called bedwetting or sleepwetting—is more common than daytime wetting. Experts do not know what causes nighttime incontinence. Young people who experience nighttime wetting are usually physically and emotionally normal. Most cases probably result from a mix of factors including slower physical development, an overproduction of urine at night, a lack of ability to recognize bladder filling when asleep, and, infrequently, anxiety. For many, there is a strong family history of bedwetting, suggesting an inherited factor.
Slower Physical Development
Between the ages of 5 and 10, bedwetting may be the result of a small bladder capacity, long sleeping periods, and underdevelopment of the body’s alarms that signal a full or emptying bladder. This form of incontinence will fade away as the bladder grows and the natural alarms become operational.
Excessive Output of Urine During Sleep
Normally, the body produces a hormone that can slow the production of urine. This hormone is called antidiuretic hormone, or ADH. The body normally produces more ADH at night so that the need to urinate is lower. If the body doesn’t produce enough ADH at night, the production of urine may not be slowed down, leading to bladder overfilling. If a child does not sense the bladder filling and awaken to urinate, then wetting will occur.
Experts suggest that anxiety-causing events occurring in the lives of children ages 2 to 4 might lead to incontinence before the child achieves total bladder control. Anxiety experienced after age 4 might lead to wetting after the child has been dry for a period of 6 months or more. Such events include angry parents, unfamiliar social situations, and overwhelming family events such as the birth of a brother or sister.
Incontinence itself is an anxiety-causing event. Strong bladder contractions leading to leakage in the daytime can cause embarrassment and anxiety that lead to wetting at night.
Certain inherited genes appear to contribute to incontinence. In 1995, Swedish researchers announced they had found a site on human chromosome 13 that is responsible, at least in part, for nighttime wetting. If both parents were bedwetters, a child has an 80 percent chance of also being a bedwetter. Experts believe that other, undetermined genes also may be involved in incontinence.
Obstructive Sleep Apnea
Nighttime incontinence may be one sign of another condition called obstructive sleep apnea, in which the child’s breathing is interrupted during sleep, often because of inflamed or enlarged tonsils or adenoids. Other symptoms of this condition include snoring, mouth breathing, frequent ear and sinus infections, sore throat, choking, and daytime drowsiness. In some cases, successful treatment of this breathing disorder may also resolve the associated nighttime incontinence.
Finally, a small number of cases of incontinence are caused by physical problems in the urinary system in children. Rarely, a blocked bladder or urethra may cause the bladder to overfill and leak. Nerve damage associated with the birth defect spina bifida can cause incontinence. In these cases, the incontinence can appear as a constant dribbling of urine.
What causes daytime incontinence?
Daytime incontinence that is not associated with urinary infection or anatomic abnormalities is less common than nighttime incontinence and tends to disappear much earlier than the nighttime versions. One possible cause of daytime incontinence is an overactive bladder. Many children with daytime incontinence have abnormal elimination habits, the most common being infrequent voiding and constipation.
An Overactive Bladder
Muscles surrounding the urethra—the tube that takes urine away from the bladder—have the job of keeping the passage closed, preventing urine from passing out of the body. If the bladder contracts strongly and without warning, the muscles surrounding the urethra may not be able to keep urine from passing. This often happens as a consequence of urinary tract infection (UTI) and is more common in girls.
Infrequent voiding refers to a child’s voluntarily holding urine for prolonged intervals. For example, a child may not want to use the toilets at school or may not want to interrupt enjoyable activities, so he or she ignores the body’s signal of a full bladder. In these cases, the bladder can overfill and leak urine. In addition, these children often develop UTIs, leading to an irritable or overactive bladder.
Some of the same factors that contribute to nighttime incontinence may act together with infrequent voiding to produce daytime incontinence. These factors include
small bladder capacity
pressure from a hard bowel movement (constipation)
drinks or foods that contain caffeine, which increases urine output and may also cause spasms of the bladder muscle, or other ingredients to which the child may have an allergic reaction, such as chocolate or artificial coloring
Sometimes overly strenuous toilet training may make the child unable to relax the sphincter and the pelvic floor to completely empty the bladder. Retaining urine, or incomplete emptying, sets the stage for UTIs.
Reprinted with the permission of the National Institute of Mental Health. © 2008 NIMH.