Introducing sleep in the Nocturia Resource Centre
By Prof. Donald Bliwise
Most urologists recognize that sleep plays an important role in the definition of ICS nocturia (“each void is preceded and followed by sleep”) (1), but for many, sleep becomes relegated to a single, unified state without much more interest or thought given to it. In fact, sleep researchers have spent years describing, both qualitatively and quantitatively, various aspects of sleep. As introduction to my role as Nocturia Resource Center Associate Editor and as a someone who has been active in the sleep research field for 40 years, I wanted to take a few moments to begin to paint a picture of just a few aspects of what we have learned about this wonderful and often delightful, but also frustrating and complex, portion of respite in our daily lives. In discussing sleep issues with the small number of academically vibrant urologists that I have had the privilege of speaking with to date, I have developed some sense of the kind conceptions about sleep that are pervasive. To that end, I thought that I might take this opportunity to talk a bit about them.
Demystifying sleep begins with breaking it down to its various dimensions. I was once told that indigenous peoples north of the Arctic Circle have dozens of different words for snow. Sleep is a lot like that. Researchers often make distinction between dimensions and textures of sleep, such as its duration, its quality, its continuity, and its depth. All of these adjectives have been subject to measurement. Moreover, those measures vary as to whether they depend on an individual’s self-report, instrumented measurements with techniques such as polysomnography or actigraphy, or even in some cases (particularly for infants and dementia patients), behaviorally based observations. Just to make matters more complicated, sleep experts frequently disagree on how best to make such measurements, how to define various metrics and what the magnitude of agreement among such variables is necessary and/or sufficient. Issues such as these represent challenges for those of us in academic sleep medicine to provide metrics that are simple and clear and make sense to both patient and physician. Developments in the area of nocturia and sleep may actually serve to herald potentially new and important ways of contributing to this data base.
I have been particularly struck by the tendency for many individuals engaged in nocturia research to embrace the concept of “bother.” For some urologists, if nocturia is not a “bother” then it may not warrant treatment or intervention. This strikes me a bit like the patient walking in the physician’s office with a blood pressure of 220/120, being told that they are seriously hypertensive , then their telling the doctor that they are not bothered by it and the physician deciding that they do not require treatment. Ultimately, whether the patient is “bothered” by his or her hypertension becomes irrelevant. This assumes, of course, that components of disturbed sleep could impact health as much as uncontrolled essential hypertension. As we hope to highlight in the months to come in the Nocturia Resource Center, the health impact of nocturia associated with disturbed sleep may indeed be no less profound than those associated with cardiovascular, metabolic or other chronic disease states.
One aspect of sleep that has not escaped the attention of some urologists interested in nocturia is sleep apnea. In his thorough lecture found elsewhere in the online Nocturia Resource Center, Alan Wein notes that, if one is looking at conditions whose treatment may be associated with rapid reversibility of nocturia and produce big effects, sleep apnea may well be at the top of the list. Indeed, sleep apnea is exceedingly common in both men and women (in middle aged adults in a ratio probably approaching 2:1 (2) and increases in the elderly (3), with gender differences less conspicuous in older age. Although mechanisms of excess urine production remain subject to debate (but are often thought to involve excess production of ANP) (4), treatment of the condition, typically with positive airway pressure delivery during sleep results in decreased urination (5). This reversibility far exceeds the effects of most pharmacologic agents and should always be examined as a possible unrecognized cause of nocturia. Definitive diagnosis typically requires some type of physiologic measurement, though traditional laboratory-based polysomnography may no longer be essential for the diagnosis (6). But even without access to such kinds of measurements, an office-based urology practice can make headway screening for sleep apnea using simple questionnaires (Berlin Questionnaire) (7) or combined survey/body habitus (Body Mass Index) screening approaches (STOP-BANG; Multivariable Apnea Prediction) (8, 9). Beneficial effects of treating sleep apnea need not be limited to nocturia, and may also encompass relevant health related conditions such as hypertension (10) and insulin resistance (11, 12).
In future editions of the Nocturia Resource Center, we will discuss other aspects of sleep and how the urologist treating patients with this exceedingly common condition can incorporate such knowledge more effectively into clinical practice.
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