March 23, 2023

When you have to wake up at night in order to urinate, you have a symptom called nocturia. It is not a disease by itself, but it can affect your health and quality of life if you wake up to void (urinate or micturate) two or more times a night.

Occurrence of nocturia varies according to gender and age. More women than men have nocturia among those aged 18 to 49 years old, and occur more in men than in women after the age of 60. About half of adults between ages 50 to 79 years have the symptom.

Studies estimate that voiding at night occurs at least twice a night among men at age 70 to 79 years. Among pregnant women nocturia is common, but this nearly always disappears three months after the pregnancy. 

Medical illnesses associated with nocturia include high blood pressure, obesity, diabetes mellitus (poorly controlled), obstructive sleep apnea, enlargement of the prostate gland, and heart failure.

Nocturia can lead to the following: a person wakes up at night to void but the amount of urine is quite small (low-volume bladder void). This may be due to an overactive bladder or obstruction of the passageway of urine most commonly by an enlarged prostate gland. Age-related changes in the bladder also lead to its reduced capacity to contain higher volume of urine. Small amount of urine would trigger the urge to urinate.

In some people, there may also be increased amount of urine voided at night due to nocturnal polyuria. Among older persons, there is decrease in the level of the hormone vasopressin at night.

The level of this hormone is normally higher at night than at daytime, leading to decreased urine output at night. Sleep disturbance is one of the most distressing symptoms in older men with prostatic enlargement and can affect quality of life. 

Nocturia can also occur when there is actual increase in daily urine output to more than three liters per day (Normal urine output is 1 to 2 ml per kilogram body weight per hour or equivalent to an average of one to two liters per day) and this is called nocturnal polyuria.

The reasons for nocturnal polyuria are the following: Large fluid intake more than 40 cc per kg body weight per day (example: 2,400 cc for a 60kg person) – this could be self-initiated, related to vigorous physical exercise, due to history of kidney stone or it may be psychogenic in which a person can drink 10 liters or more of fluids per day.

Obstructive sleep apnea creates negative pressure inside the thorax, leading to the release of a substance from the heart (atrial natriuretic protein) which promotes excretion of sodium and water and hence increase in the volume of urine at night. 

In heart failure and generalized edema (nephrotic syndrome) or venous insufficiency (like in the legs) there is increase in the amount of fluid in the body. This excess edema is found outside blood vessels so called extravascular or third space. When the patient lies down, some of this excess fluid goes inside the blood vessels (intravascular space) and hence can be brought back to the heart then pumped to the kidneys.

In diabetes mellitus, increase in blood sugar levels causes spillage of sugar into the urine. Sugar draws water with it leading to frequent urination usually with increase in urine volume.

Women who suffer from nocturia also have other urinary problems like overactive bladder or frequent urination at daytime. Among postmenopausal women, hormonal changes especially reduced estrogen levels have a role.

Other causes of nocturia are the following:

Intake of beverages that promote voiding: caffeine, alcohol

Medications: diuretics, xanthines, beta blockers, cholinesterase inhibitors

Depression – Data from some studies have shown that nocturia is strongly associated with higher onset of depression, and that depression itself is also strongly associated with nocturia. It has also been shown that nocturia poses a greater risk for depression in men than in women. 

Management of nocturia are the following: 

1. Treatment of any underlying disease that causes nocturia or nocturnal polyuria. 

2. Avoidance of coffee, alcohol, and other diuretic fluids.

3. Night time diuretics prescribed for medical illness may be taken earlier at mid afternoon.

4. Elevate edematous legs in the afternoon, or wear compression stockings.

5. Adequate control of diabetes mellitus. 

6. Before bedtime, urinate while sitting on the toilet, leaning slightly forward, wait for 20 to 30 seconds to urinate again. This is effective both in men and in women.

7. Kegel exercises which strengthen the pelvic floor are helpful both for men and women. They have been shown to reduce nocturia.

8. Reducing overall fluid intake, with precautions if fluid management is part of a treatment for other illnesses.

8. Treatment of benign prostatic hypertrophy with drugs or surgery

Difficulty returning to sleep because of nocturia can lead to feelings of tiredness or fatigue, work absenteeism, high rates of accidental falls at night. Seek medical consult for early work-up and management.