Nocturia is the medical term for the need to awaken from sleep to urinate. Getting up once to relieve your bladder during sleep hours is usually not particularly troublesome. However, when it happens two or more times it can negatively impact one’s quality of life because of sleep disruption, an increased risk of fall-related nighttime injuries, daytime fatigue and an increased risk of fatigue-related accidents.
What causes nocturia?
Nocturia correlates with aging and the associated decline in kidney function and decreased ability to concentrate urine. Although having an enlarged prostate may contribute to nocturia, it’s much more complicated than that since women do not have prostates and nocturia is equally prevalent in men and women.
Nocturia is based on multiple factors that require careful evaluation in order to sort out and treat appropriately. As a urologist, my goal is to distinguish between urological and non-urological causes for nighttime urinating. It often comes down to one of three factors:
- Nighttime urine production by the kidneys
- Urinary bladder capacity
- Sleep status.
In the elderly population, excessive nighttime urine production is a factor almost 90% of the time.
Nocturia can be classified into 5 categories:
- Global polyuria (making too much urine, day and night)
- Nocturnal polyuria (making too much urine at night)
- Sleep disorders
- Reduced bladder capacity
Global polyuria can result from excessive fluid intake or from dehydration from poorly controlled diabetes mellitus. The pituitary gland produces an important hormone responsible for water regulation — ADH (anti-diuretic hormone) — and it works by giving the message to the kidneys to concentrate urine. Diabetes insipidus is a disease of either kidney origin in which the kidneys do not respond to ADH, or pituitary origin in which there is deficient secretion of ADH. In either case, lots of urine will be made, resulting in frequent urination, both daytime and nighttime. Medications including diuretics, SSRIs (selective serotonin reuptake inhibitors), calcium blockers, tetracycline and lithium may induce global polyuria.
Nocturnal polyuria may be on the basis of excessive fluid intake, especially diuretic beverages including caffeine and alcohol. It may also occur because of a nocturnal defect in the secretion of ADH, and unresponsiveness of the kidneys to the action of ADH. Congestive heart failure, sleep apnea and kidney insufficiency also may play a contributory role. Certain conditions result in accumulation of fluids in the tissues of the body, particularly the legs (peripheral edema); when lying down to sleep, the fluid is no longer under the same pressures as determined by gravity, and returns to the intravascular (within the blood vessels) compartment. It is then subject to being released from the kidneys as urine. Such conditions include heart, kidney and liver impairment, nephrotic syndrome, malnutrition and venous stasis.
Primary sleep disorders may also cause nocturia, including insomnia, restless leg syndrome, narcolepsy, and arousal disorders (sleepwalking, nightmares, etc.)
Reduced bladder capacity may be caused by numerous urological issues. Many processes can occur within the bladder that can irritate its delicate lining, causing a reduced “functional” capacity: bladder infections, bladder stones, bladder cancer, bacterial cystitis, radiation cystitis, and interstitial cystitis.
An overactive bladder—a bladder that “squeezes without its owner’s permission”—can give rise to nocturia. Some people have small “anatomical” bladder capacities on the basis of scarring, radiation, or other forms of damage. Prostate enlargement commonly gives rise to nocturia, as can many neurological diseases that often have profound effects on bladder function. Incomplete bladder emptying can give rise to frequent urination since the bladder is already starting out on the bias of being partially filled. Incomplete emptying is often seen with prostate enlargement, scar tissue in the urethra, neurologic issues, and bladder prolapse.
How is nocturia diagnosed?
The key diagnostic tool for nocturia is the frequency-volume chart (FVC), a simple test that can effectively guide diagnosis and treatment. This is a 24-hour record of the time of urination and volume of urination, requiring a clock, pencil, paper and measuring cup. Typical bladder capacity is 10–12 ounces with 4–6 urinations per day.
How is nocturia treated?
Lifestyle modifications to improve nocturia include:
- Preemptive voiding before bedtime
- Intentional nocturnal and late afternoon dehydration
- Salt restriction
- Dietary restriction of caffeine and alcohol
- Adjustment of medication timing
- Use of compression stockings with afternoon and evening leg elevation
- Sleep medications
Urological issues may need to be managed with medications that relax or shrink the prostate when the issue is prostate obstruction, and bladder relaxants for overactive bladder. For nocturnal polyuria, synthetic ADH can be highly effective.
Bottom Line: Nocturia should be investigated to determine its cause, which may often in fact be related to conditions other than urinary tract issues. Nighttime urination is not only bothersome, but may also pose real health risks. Chronically disturbed sleep can lead to a host of collateral wellness issues.