Nighttime Urination

By: Harvard Men's Health Watch (Wednesday, 27-11-2002)

Doctors call it nocturia. Men call it a curse. Either way, nighttime urination is a common problem, particularly as we age.

Doctors used to blame nocturia on benign prostatic hyperplasia (BPH), and urologists often favored surgery to correct the problem. But many men who underwent a technically successful transurethral resection of the prostate (TURP) still found themselves stumbling to the bathroom at night. Now we know why: New research shows that nocturia has many causes, and enlargement of the prostate is actually rather low on the list. It's a rude awakening, but it offers a rational approach to the future treatment of nocturia.

Boys and Girls Together

If nocturia was caused principally by BPH, it would be much more common in men than women. But many surveys demonstrate that the problem is equally prevalent in both genders. A survey of 400 American men and 479 women who were healthy and 60 years of age or older tells the tale: 65.2% of the men and 62.8% of the women reported nocturia. In addition, the number of nighttime trips to the bathroom was similar for both: About one-quarter of the subjects reported voiding two or more times in a typical night.

An Age-Old Problem

Gender does not account for nocturia, but age does. In both men and women, nighttime urination increases steadily over the years. A 12-month Austrian study of 1,247 women and 1,221 men illustrates the relationship: Below the age of 30, 3.1% of women and 3.4% of men reported nocturia; for ages 30–59, 7.2% of women and 5.7% of men experienced the problem, and at age 60 and beyond the figures were 26.7% for women and 32.4% for men. In this study, as in others, nocturia was equally bothersome for men and women, and nearly two-thirds of both sexes reported that getting up at night had a negative effect on their lives.

Why is nocturia related to age? Many factors contribute, including changes in urine production by the kidneys, changes in the capacity and reactivity of the bladder, changes in the quality of sleep, and the presence of disease, both in the urinary tract and in the rest of the body.

In the Flow

In many cases, nocturia is explained by an increase in urine production; some people get up simply because they have more urine to eliminate. The reason for the high volume may be as simple as excessive fluid intake, particularly late in the day. Patients who take diuretic medications in the afternoon or evening will also have a high urine flow at night. And because alcohol and caffeine are diuretics, a cocktail before dinner or espresso with dessert can also trigger nocturia.

But even without coffee, alcohol, medications, or lots of liquids, many older people produce excessive amounts of urine at night. Infants and young children produce urine at a steady rate around the clock. But after the age of 7 or so, things change as the body develops ways to protect sleep. Healthy young adults produce urine three times faster during the day than at night. That's because the brain puts out extra amounts of antidiuretic hormone (ADH, also known as vasopressin) at night; ADH causes the kidneys to reabsorb water, so they produce small volumes of concentrated urine. You'll know ADH is at work if you sleep through the night and wake up to void a moderate amount of concentrated, dark yellow urine. But as people age, the circadian rhythms that control salt and water excretion (among other things) begin to change. As a result of changes in ADH and other hormones such as atrial natriuretic peptide, many older people revert to the juvenile pattern of steady urine production around the clock. True, they void less during the day, but they pay for that convenience by voiding more at night.

The Bladder's Role

Changes in the bladder also contribute to nocturia in older adults. With age, the bladder tends to get smaller and stiffer. It also becomes more sensitive to the presence of urine, so it produces the urge to void before it's really full. Bladder infections and inflammation make the problem even worse. BPH also produces excessive bladder activity.

If you pass large volumes of clear urine when you get up at night, you can suspect increased urine production as the cause. If you wake up with the urge to void but pass only a modest amount of yellow, more concentrated urine, an overactive bladder is probably to blame. In many people, though, both problems contribute to nocturia.

Sleep and the Nervous System

The urge to urinate is the result of a complex balance of influences. When its muscles are relaxed, the bladder wall is soft and stretchy; pressure doesn't even start to build up until the bladder is half full, and the desire to urinate doesn't begin until it is three-quarters full. As the bladder gets fuller, it sends nerve impulses to the brain, signaling the need to void. But the brain talks back, suppressing the urge until it's convenient or until the bladder is totally full.

When people wake up at night to urinate, they assume that they have a full bladder. In some cases they're right. But as people get older, they often sleep lightly, so instead of suppressing the urge to void until morning, they may sense the urge even before the bladder is three-quarters full; nocturia may be the effect of disrupted sleep, not its cause.

Surprisingly, perhaps, people are very poor judges of what wakes them up. When researchers monitored 80 patients with suspected sleep disorders, they recorded an average of one-and-a half episodes of urination per night. In most cases, the patients said they were awakened by the urge to void, but careful monitoring documented that sleep disturbances were actually responsible for 79% of the awakenings. In men, the major cause was obstructive sleep apnea (see Harvard Men's Health Watch, May 1997); restless legs syndrome was a frequent cause in both sexes (see HMHW, December 1998). Anxiety and various neurological disorders can also contribute to disturbed sleep and nighttime urination, as can insomnia (see HMHW, April and May 1999) and simple habit.

Other Diseases

In most cases, nighttime urination is harmless and innocent, even if doctors give it a fancy name like nocturia. But in some situations it can reflect important diseases outside the urinary tract. The two most common are diabetes mellitus and congestive heart failure. In the former, sugar in the urine causes an increase in urine volume; in the latter, an increased excretion of sodium when the patient lies down is responsible. Although these problems are relatively uncommon, they should remind people who have nocturia to discuss the symptom with their doctors; as it is, many don't.

The Prostate, Too

Even if BPH is not the culprit it was once thought to be, it is still an important cause of nocturia. But when BPH is responsible, men experience other symptoms as well. Urinary urgency, frequency, and hesitancy, incomplete bladder emptying, a slow or narrow urinary stream, and dribbling at the end of urination are typical (see HMHW, March 1998). Even when these symptoms suggest that BPH is responsible for nocturia, they don't automatically require treatment. Instead, men need treatment only if the symptoms are bothersome enough to detract from their quality of life; men who fall back to sleep after they void and wake up feeling rested in the morning don't need treatment. And even if nocturia produces sleep deprivation, medical treatment with alpha blockers, finasteride, or even herbs should be considered alternatives to standard prostate surgery and the newer, less invasive surgical therapies.

Medication for BPH

Treating BPH used to mean a trip to the operating room. That's no longer true. While surgery remains an effective therapy (see HMHW, August 1998), men who are bothered by symptoms of BPH can consider three types of medication, which can be used singly or in combination.

Alpha blockers relax the muscles in the prostate and bladder neck, easing the flow of urine in about 70% of men with BPH. Doxazosin (Cardura) and terazosin (Hytrin) are usually taken at bedtime. Because both can lower the blood pressure, doctors usually start with a 1 mg dose, then gradually increase it to a maximum of 8 mg (doxazosin) or 10 mg (terazosin). The newest alpha blocker, tamsulosin (Flomax), is less likely to affect the blood pressure; the usual dose is 0.4 or 0.8 mg taken 30 minutes after the evening meal.

Unlike the alpha blockers, finasteride (Proscar) actually shrinks the prostate gland. Unfortunately, it takes many months to work, and it's likely to help only men with rather large glands. The usual dose is 5 mg a day. Finasteride lowers the PSA, sometimes complicating screening for prostate cancer, and it causes reversible erectile dysfunction in a small percentage of men.

Herbs can also help some men with bothersome BPH. The best studied is Serenoa repens, better known as saw palmetto. Because it is sold as a dietary supplement, it is exempt from FDA standards for purity, efficacy, and safety. But many clinical trials, mostly conducted in Germany, suggest that it can reduce the symptoms of BPH with few side effects.

Up and Down

Nocturia is complex, but a few simple adjustments can help you manage the problem, whatever its cause. Here are a few tips:

• Don't drink too much. Fluids are important for health (see HMHW, September 2000), but unless you have kidney stones, urinary tract infections, or certain other medical problems, you don't have to force fluids. Drink enough to quench your thirst and maintain good hydration, but drink as little as possible within 4 to 5 hours of bedtime.
• Reduce your intake of alcoholic and caffeinated beverages, particularly late in the day.
• Review your medications. If you are taking a diuretic, ask your doctor if a milder preparation or another type of drug would be as good for you—but don't make changes on your own. And while you're at it, ask your doctor to be sure you don't have diabetes or any other condition that might increase your urine flow.
• Establish good sleeping habits. Don't eat a large meal before you retire. Be sure your bed is comfortable and your bedroom is dark, quiet, and at the right temperature. Particularly if you have a large neck or snore loudly, ask your doctor if a sleep disturbance could be the real reason you're getting up at night.
• Protect yourself from falls at night. Be sure your path to the bathroom isn't an obstacle course; loose rugs and stray objects can turn nocturia into a broken hip. Use a nightlight bright enough for safety but dim enough to allow you to get back to sleep. And be sure to follow the same program when you're away from home.

Nighttime urination can be caused by BPH or a variety of other problems—but even more often, it's a normal consequence of the aging process. With a little planning, most men can minimize the number of times they get up at night and maximize their ability to get back down for a refreshing night's sleep.