Prevalence of Sleep Apnea in Males with Nocturia
Approximately 75-80% of adult males with nocturia have obstructive sleep apnea, with the association being strongest in men under 50 years of age. 1, 2
Evidence from Clinical Studies
Overall Prevalence Data
In a landmark polysomnography study of 80 consecutive patients with nocturia (awakening at least once to urinate), 79.3% of awakenings were directly caused by sleep apnea, snoring, or periodic leg movements rather than bladder pressure. 2
Among 1,757 men referred for sleep evaluation, nocturia frequency correlated significantly with the apnea-hypopnea index (AHI), though this relationship was modified by age. 3
In a prospective study of 274 OSAS patients treated with CPAP, 76.4% reported at least one nocturia episode before treatment, with 73.0% experiencing clinically relevant nocturia (≥2 voids per night). 4
Age-Specific Patterns
The relationship between sleep apnea and nocturia is particularly strong in younger men:
In men under 50 years of age, the AHI was significantly higher in those with nocturia compared to those without (P <0.005), and nocturia occurred without other voiding symptoms, suggesting OSA as the primary cause. 5
Multiple regression analysis in men <65 years showed that AHI independently predicted pathological nocturia (OR 1.02, P <0.001), along with age and benign prostatic hypertrophy. 3
However, in men ≥65 years, sleep apnea parameters showed no significant relationship with nocturia frequency, as age-related urinary diseases and voiding dysfunction override the influence of OSA. 3
Clinical Phenotype Characteristics
Males with both nocturia and OSA represent a distinct phenotype of more severe disease:
Nocturic OSA patients had significantly higher AHI (64.8 ± 35.9 vs. 43.9 ± 29.1; P <0.001), higher Epworth Sleepiness Scale scores (9.2 ± 5.3 vs. 7.7 ± 4.4), and lower nadir oxygen saturation during sleep. 6
A history of nocturia (≥2 voids/night) increased the odds of very severe OSA (AHI >60) by 2.4 times (95% CI 1.086-5.434, P = 0.031). 6
Time between bedtime and first urination was significantly shorter in very severe OSA (2.4 ± 0.9 hours) compared to severe OSA (3.1 ± 1.3 hours) and mild-to-moderate OSA (3.0 ± 1.1 hours). 6
Diagnostic Pitfall: Patient Misattribution
A critical clinical caveat is that patients are extremely poor judges of why they awaken to urinate:
Patients correctly identified the source of their awakening in only 4.9% of cases, with sleep apnea correctly cited only once out of 121 awakenings. 2
The fact that patients urinate once awake contributes to faulty post hoc reasoning, leading both patients and physicians to incorrectly attribute awakenings to bladder pressure rather than sleep-disordered breathing. 2
The American Geriatrics Society recognizes nocturia as a symptom of OSA, along with excessive daytime sleepiness, snoring, observed apnea, and morning headache. 1
Treatment Response
CPAP treatment significantly reduces nocturia in males with OSA: