Sleep plays an important role in the ICS definition of nocturia (‘each void is preceded and followed by sleep’). Nocturia can be caused by primary sleep disorders such as sleep apnoea, snoring, restless legs syndrome or periodic leg movements, but anxiety and depression may also cause nocturnal awakenings and subsequent voiding. Primary nocturia (not caused by sleep disorders) will cause secondary sleep disruption and this adversely affects quality of life, daytime activities, cognition, mental health or mood and productivity. The cognitive and behavioural consequences of sleep disruption are likely to be obvious in the short term but other consequences such as vulnerability to metabolic and cardiovascular conditions and perhaps even an increased risk of death may become evident in the longer term. Besides the disruption itself and the frequency of nocturia the timing of waking up is also important. The first half (3–4 hours) of the night includes periods of deep, slow-wave sleep and interrupting it reduces insulin sensitivity and attenuates the sleep-related decrease in blood pressure. Patients with untreated nocturia generally wake for their first void about 2.5 hours after going to bed thus reducing their crucial slow-wave sleep duration. The shortening of the slow-wave sleep period has been linked to reduction of global duration of sleep and sleep quality and increases daytime dysfunction. Therefore, treatment in primary nocturia should aim at specifically targeting the causative mechanism(s) of nocturia and this is likely to have a better effect on the patient’s sleep than using a sedative-hypnotic drug. As a consequence, in patients with nocturia primary and secondary causes for sleep disturbances should be evaluated.
Nevertheless, 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 Centre Associate Editor, and as 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 into its various dimensions. I was once told that indigenous people 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), behaviourally 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 and 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 Centre, 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 Centre, Alan Wein notes that if one is looking at conditions whose treatment may be associated with rapid reversibility of nocturia and produce big effects then 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 unrecognised cause of nocturia. Definitive diagnosis typically requires some type of physiologic measurement although 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 Centre, 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.
Philip E. V. Van Kerrebroeck
Professor of Urology and urologist at the University of Maastricht, and the Maastricht University Medical Centre (NL). He obtained his MD from the University of Louvain (B), trained in General Surgery and Urology in Belgium, the Netherlands and the USA and received a MMS Degree (University of Antwerp, B) and a PhD Degree (Radboud University Nijmegen, NL). He has a clinical interest in different forms of lower urinary tract problems and his research includes new therapies in Neuro-Urology and Functional Urology. For 8 years he was Chairman of the Standardisation Committee of the ICS and authored the ICS report on Nocturia. He was involved in the NERI Conferences on Nocturia and was Chairman of the ICI-RS Nocturia Think Tank. He is editor of the EAU-Nocturia Resource Centre and is Chairman of the History Office of the EAU. He is a member of 25 scientific societies, serves on the editorial board of 6 journals, and has authored over 350 peer-reviewed articles, book chapters and books.