Why People Have to Pee during the Night

Nocturia is defined as “excessive urination at night”. Normally, the amount of urine the body produces goes down at night, reducing the need to urinate for the 6 to 8 hours that people are sleeping. Since waking to urinate on one occasion during the night is generally considered to be “normal”, having nocturia generally implies that someone wakes up more than once a night to urinate.
   
Nocturia becomes more common as people age with some surveys finding that over half of men and women over the age of 60 have this complaint.  In addition to being associated with a number of medical problems, nocturia can result in sleep deprivation and an increased risk for developing depression. Particularly in the elderly, getting up during the night to urinate can also cause accidental falls and fractures.

Causes of Nocturia:

1. Advancing age:  Antidiuretic hormone (ADH), released from the pituitary gland in the brain, causes the kidneys to hold onto water, reducing urine volume.  Normally, ADH production increases while someone is sleeping thus decreasing the amount of urine produced.  In the elderly, ADH levels have been noted to decrease at night, resulting in increased urine volume and the need to urinate.
    
2. Drinking too much fluid during the evening.  Consuming caffeine or alcohol-containing beverages after dinner will contribute to this even further.
    
3. Infection of the bladder or urinary tract.  When present, this usually causes (UTI) symptoms, such as burning or stinging during urination or blood in the urine.
    
4. Enlarged prostate gland (BPH). This is one of the most common causes in older men. With ageing, the prostate increases in size which causes blockage of the flow of urine. The response to this blockage is thickening of the muscular walls of the bladder and subsequent reduction in the size of the bladder and capacity to hold urine. Known as “prostatism”, symptoms of an enlarged prostate gland include nocturia, the need to urinate urgently, and dribbling after urination.
    
5.  Diabetes mellitus. In poorly controlled diabetes mellitus, high levels of glucose in the bloodstream can cause increased urination (osmotic diuresis). This can lead to a vicious cycle of dehydration, increased water consumption and polyuria (frequent urination).
    
6. “Third Spacing”.  This term refers to the movement of fluid from inside the blood vessels into the interstitial space (between the cells of the body).  This results in fluid retention, usually in the legs (edema) or abdomen (ascites). Congestive heart failure, venous disease of  the lower extremities, and high intake of salt are some of the most common causes of third spacing.
    
7. Certain medications. Foremost among these are diuretics (water pills), taken for a number of medical problems including heart failure and hypertension. Others that can potentially cause nocturia include digitalis (a heart medication), lithium (used in the treatment of bipolar disorder) and Dilantin (also known as phenytoin, an anti-seizure medication).
    
8. Sleep apnea. In this condition, partial obstruction of the airway leads to low oxygen content and constriction of blood vessels in the lungs. This stimulates the release of a hormone that is responsible for increasing urine production.  

Evaluation of Nocturia.  It is important to note that nocturia is a symptom, not a specific disease.  While aging can be responsible for causing nocturia, it should not necessarily be assumed that it is always due to “getting old”. There are a number of medical conditions that can cause someone to have to urinate more than once during the night.  Determining the underlying cause can be quite challenging with the evaluation touching on causes as diverse as congestive heart failure, sleep apnea, prostate enlargement and diabetes. Use of a “voiding diary” and measurement of urine volumes during the day and night can help with determining the underlying cause.

Treatment of Nocturia.  Treatment for nocturia is directed at the underlying cause. For example, improvement in blood sugars can help in uncontrolled diabetes. If an obstructing prostate gland is the cause, a medication or surgery to reduce the size of the prostate will help. The use of continuous positive airway pressure (CPAP) in someone with sleep apnea can reduce associated nocturia. In a rare condition known as diabetes insipidus, use of a synthetic version of antidiuretic hormone (desmopressin) will help. If taking diuretic medication is responsible, the medication administration may need to be moved to earlier in the day to avoid having to void during the night.

When the underlying cause is not serious enough to warrant specific treatment, several lifestyle measures may help:

• Limit fluid intake 3 hours prior to bedtime
   
• Restrict consumption of coffee, caffeinated beverages, and alcohol in the evening.
   
• Elevate legs in the evening to help prevent the development of lower extremity edema.
   
• Wear compression stockings if venous disease is causing fluid accumulation.
   
• Pre-emptive voiding prior to going to bed may delay the need to urinate during the night.