Sleep Apnea and Nocturia/Dysuria
Sleep apnea, specifically obstructive sleep apnea (OSA), is a well-established cause of nocturia, but it does not cause dysuria. 1
OSA as a Recognized Cause of Nocturia
Obstructive sleep apnea is explicitly listed as a key medical condition that causes nocturia in the European Association of Urology's PLANET guidance. 1 OSA appears in the "SCREeN" framework (Sleep medicine, Cardiovascular, Renal, Endocrine, and Neurology) as one of the primary sleep medicine conditions that must be evaluated when assessing nocturia. 1
Mechanism of OSA-Related Nocturia
OSA causes nocturnal polyuria through a specific physiological mechanism: negative intrathoracic pressure during inspiratory effort against a closed airway leads to cardiac distension, which triggers release of atrial natriuretic peptide. 2
This cardiac hormone increases sodium and water excretion and inhibits vasopressin and the renin-angiotensin-aldosterone system, resulting in increased urine production during sleep. 2
The commonly held theory of false cardiac overload signaling has limitations, and the actual mechanisms are complex, involving autonomic nervous system dysfunction, oxidative stress, and endothelial damage. 3
Clinical Evidence Supporting the Link
Patients with nocturia demonstrate more severe OSA compared to those without nocturia (apnea-hypopnea index 52.0 vs 44.7). 4
In younger patients (<50 years old), OSA severity correlates significantly with the number of nighttime urinations, and these patients often have nocturia without other voiding symptoms. 4
Treatment with continuous positive airway pressure (CPAP) reduces nocturia in 75-90% of patients with OSA, with the greatest benefit seen in those with severe disease. 4
CPAP treatment can substantially reduce nocturia when patients tolerate and consistently use the therapy, though compliance remains a significant challenge. 1
Screening for OSA in Patients with Nocturia
When evaluating nocturia, clinicians should actively screen for undiagnosed OSA using specific questions: 1, 5
"Have you been told that you gasp or stop breathing at night?" 1
"Do you wake up without feeling refreshed? Do you fall asleep in the day?" 1
"Do you have problems sleeping aside from needing to get up to urinate?" 1
For suspected OSA, use the STOP-BANG questionnaire and consider referral for overnight oximetry. 1, 5
Dysuria and Sleep Apnea
There is no established relationship between sleep apnea and dysuria (painful urination). Dysuria indicates local urinary tract pathology such as infection, inflammation, or structural abnormalities—conditions unrelated to OSA pathophysiology. The evidence provided contains no mention of dysuria as a symptom of sleep apnea. 1, 3
Common Pitfalls to Avoid
Failing to distinguish between nocturia caused by urologic disorders versus OSA is a critical error, particularly in younger patients without other lower urinary tract symptoms. 5, 4
Assuming CPAP treatment is effective simply because equipment was prescribed—many patients do not tolerate or consistently use CPAP, so referral letters mentioning CPAP do not guarantee the patient is actually using it. 1
Overlooking sleep disorders as contributors to nocturia leads to inappropriate urologic treatment when the underlying cause is OSA. 5, 6
In patients with both OSA and nocturia, prioritize treating the OSA first, as this may resolve the nocturia without additional urologic intervention. 1, 4