What Causes Nighttime Incontinence?
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.
Reprinted with the permission of the National Institute of Mental Health. © 2008 NIMH.