Nocturia (derived from Latin nox, night, and Greek [τα] ούρα, urine), also called nycturia (Greek νυκτουρία), is the need to get up in the night to urinate, thus interrupting sleep. Its occurrence is more frequent in pregnant women and in the elderly. Nocturia could result simply from too much liquid intake before going to bed (usually the case in the young), or it could be a symptom of a larger problem, such as sleep apnea, hyperparathyroidism, chronic renal failure, urinary incontinence, bladder infection, interstitial cystitis, diabetes, congestive heart failure, benign prostatic hyperplasia, ureteral pelvic junction obstruction or prostate cancer.
From the American Sleep Apnea Association:
Nocturia (nighttime urination) is so prevalent in sleep apnea patients it has become a screening tool as significant as snoring. A research study showed that over 84% of patients with sleep apnea reported frequent nighttime urination while 82% acknowledged snoring.
How does apnea cause nocturia? Umlauf explains that during episodes of sleep apnea, the soft structures in the throat relax and close off the airway, setting into motion a chain of physiological events. “Oxygen decreases, carbon dioxide increases, the blood become more acidic, the heart rate drops and blood vessels in the lung constrict,” says Umlauf. “The body is alerted that something is very wrong. The sleeper must wake enough to reopen the airway. By this time, the heart is racing and experiences a false signal of fluid overload. The heart excretes a hormone-like protein that tells the body to get rid of sodium and water, resulting in nocturia.”
The good news is that many people who have nocturia due to their untreated sleep apnea find that it totally resolves once they become cpap compliant.