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DEAR DR. ROACH: I’m writing regarding the recent column that mentioned frequent nighttime urination. I had a similar problem and awakened several times to urinate each night. About a year ago, I started using a CPAP for sleep apnea. Immediately after starting to use the CPAP, my nighttime urination frequency decreased. It’d range from sleeping completely through the night to waking up twice, with an average of waking up once per night.
Building off a prior column, my hypothesis was that better sleep led to a more stable production of the natural diuretic that the body makes at night. The sleep therapist concurred, but her explanation was that when the heart’s stressed by apnea, the body tries to reduce stress by decreasing fluids. As I don’t remember seeing a connection between sleep apnea and frequent nighttime urination in your column, I thought that it might be worth sending you a note. -- T.B.
ANSWER: You’re right that people with obstructive sleep apnea (OSA) often urinate at night more than others. The mechanism for the increased urination is complex, but experts think that your hypothesis is the most important one.
The natural diuretic that I think you’re referring to is called atrial natriuretic peptide (ANP). If the heart is stretched (with fluid overload, for example), a system in the atria secretes this peptide, which stimulates the kidney to get rid of excess salt and water. In people with OSA, muscles in the throat relax during sleep. In people who have an airway with a particular shape, the throat closes partially, causing snoring, or it closes completely, which is the mechanism of OSA. This attempt to breathe in against a closed airway causes negative pressure inside the chest, which causes the atria to fill up more than usual, triggering the secretion of the natural diuretic ANP.
I’m not sure how to interpret the sleep therapist’s hypothesis, but it sounds like she might be saying the same thing without specifically mentioning ANP, which stimulates the diuresis. There are changes in other systems, including the antidiuretic hormone vasopressin and the renin-angiotensin system.
If it isn’t getting enough oxygen, the body ultimately responds by waking up just enough to regain tension in the throat muscles, which allows you to breathe. Although this can happen hundreds of times per night without the person being aware of it at all, if they wake up more completely, they may feel like they need to go to the bathroom, even if their bladder isn’t completely full.
The result is that people with OSA often have to urinate many times per night, which worsens their already bad sleep schedule. Treating OSA by any effective means, such as the CPAP machine that you use, can stop or reduce the need to void so frequently.
DEAR DR. ROACH: My 97-year-old mother has an apparent urinary tract infection without symptoms. Urine cultures were positive first for Citrobacter freundii, then for E. coli. The infectious disease doctor didn’t want to treat the infections because she doesn’t have symptoms. Should she be treated? -- S.B.
ANSWER: I agree with the infectious disease doctor that urine infections without symptoms shouldn’t be treated. It’s more likely that she will be harmed by taking antibiotics rather than getting any benefit. Allergic reactions and gastrointestinal infections (especially Clostridioides difficile) can be dangerous.
However, I wonder why she had the urine tests to begin with. We recommend against testing in people without symptoms (with a few exceptions such as immediately after a kidney transplant, in newly pregnant women, or before a urological procedure). If she was having symptoms of burning or pain or symptoms of systemic infections (like fever or chills), then she’d need treatment.
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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu. (c) 2026 North America Syndicate Inc. All Rights Reserved