From the National Sleep Foundation:
Who would have thought that sleep apnea might be responsible for frequent trips to the toilet at night, but a recent study of 97 individuals (75 men and 22 women), found that individuals with sleep apnea who also experienced nocturia (frequent urination at night) benefited from continuous positive airway pressure (CPAP) treatment. Researchers at the Institute of Urology in Tel Aviv, Israel found that individuals awoke to urinate 2.5 times on average per night before treatment, and after being treated with CPAP, the majority of participants only awoke 0.7 times per night on average. Of the 97 participants, 73 reported improvement in nocturia. The results indicate that CPAP treatment for obstructive sleep apnea (OSA) may also have positive effects on nighttime urination.
Nocturia is a common symptom of sleep apnea. This has been well know to sleep specialists. This study demonstrates that CPAP is an effective treatment for this OSA symptom. One of these days I'll get around to posting an explanation of how osa causes nocturia.