Nocturia is defined by the International Continence Society (ICS) as “the complaint that the individual has to wake at night one or more times… to urinate.” There are many possible causes of nocturia and these causes vary depending on the type of nocturia. The four different types of nocturia are polyuria, nocturnal polyuria, low nocturnal bladder capacity, and mixed nocturia.
Polyuria, or excessive urination, can be caused by high fluid intake, untreated diabetes (Type 1 and Type 2), diabetes insipidus, or gestational diabetes (occurs during pregnancy). The polyuria causes you to produce a great deal of urine (more than 2 liters) a day.
Nocturnal polyuria is, “a syndrome where the usual day to night ratio of urine production is altered.” It can be caused by certain drugs (including diuretics), drinking too much fluid before bedtime (especially caffeinated or alcoholic beverages), congestive heart failure, edema of lower extremities (swelling of the legs) and sleeping disorders (such as obstructive sleep apnea.) Nocturnal polyuria causes your body to produce a large volume of urine while you sleep.
When your bladder can’t hold as much liquid at night as it can during the day, this is referred to as low nocturnal bladder capacity. It can be caused by bladder obstruction, overactivity, infection, recurrent urinary tract infection, bladder inflammation (swelling), interstitial cystitis (pain in the bladder), bladder malignancy or benign prostatic hyperplasia in men (a non-cancerous overgrowth of the prostate that obstructs the flow of urine). Low nocturnal bladder capacity can cause you to produce more urine at night than your bladder is able to hold and this leads you to wake up at night because you need to empty your bladder.
Mixed nocturia is where your bladder problems are a mixture of nocturnal polyuria and low nocturnal bladder capacity. Many patients with nocturia have this combination of mixed nocturia. The symptoms and causes of mixed nocturia are a combination of nocturnal polyuria and low nocturnal bladder capacity indications.
With a healthy bladder, you should be able to sleep for 6-8 hours without having to get up in the middle of the night to use the bathroom. However, people who have nocturia wake up more than once a night to urinate and this can cause disruptions in a normal sleep cycle.