Nocturia is associated with decreased quality of life, increased morbidity and mortality, and affects more than 70% of adults over 60. Poor sleep is comorbid with nocturia and leading to diminished daytime function, adverse cardiovascular outcomes, advancing dementia, and institutionalization. Until now we have lacked the tools to measure bladder function while sleeping. Lack of understanding of the interaction of sleep and bladder activity has limited our ability to target and treat nocturia. 

We have used a catheter-free, wireless, indwelling, bladder pressure measurement device, the nocturia monitor (NM), to measure bladder pressure continuously overnight concurrently with Zmachine®, a single channel EEG sleep monitor for home use.  Here we present, for the first time, a detailed overnight study of potential clinically useful measures and observations of bladder behavior and associated EEG/sleep stage in one older woman with nocturia and urgency urinary incontinence.

We recruited women over 60 years of age with urgency urinary incontinence and nocturia to undergo an overnight study of bladder activity using the NM and Zmachine®. Participants gave informed consent and the study was approved by the Institutional Review Board. The NM was inserted into the bladder in clinic and participants were given a Zmachine® and bladder/activity diary to complete overnight before returning to the clinic for NM removal the following day.  Continuous vesical pressure was collected over this period by the NM, and EEG and sleep stage were collected during sleep by the Zmachine®. Sleep and bladder data were aligned to within 30 seconds accuracy and each bladder event during sleep was manually noted with its associated sleep stage.

A 69 year old woman with mean 3.3 incontinence episodes/day on 3-day bladder diary and nocturia 1-2 times per night wore the NM for just over 24 hours (9am-9am) with Zmachine® worn from 11:32pm to 6:57am with a total sleep time of 5 hours and 54 minutes. During sleep, respiration was clearly seen on NM traces and bladder events with peak pressure changes as small as 7cmH2O were detectable. A total of 20 bladder events were recorded after first onset of sleep, with two occurring in the morning when sleep stage was not scored. Of these, 16 bladder events were concurrent with an awakening and EEG spike; only two identified bladder events were not concurrent with an awakening. One bladder event (3:50am) was a void, concordant with bladder diary. The Zmachine® recorded 27 awakenings; 60% of the awakenings were concurrent with bladder activity. One bladder event occurred during deep sleep (N3 stage) and one during REM (rapid eye movement) sleep, with the rest occurring during light sleep (N1/2 stage). The participant returned to light sleep in all cases (Figure 1).

This is the first time bladder and sleep events have been measured concurrently and this was done in the participants home without wires or catheters. While manual time alignment of the two simultaneous technologies currently precludes assessment of order of sleep and bladder events, we are clearly able to identify bladder events and determine association with awakenings, due to the large number of concurrent events detected. 
Bladder events tend to occur during the lighter stages of sleep and with an awakening. In this participant more than half of the awakenings are associated with a bladder event (Figure 1).

This technology allows detailed insight into bladder behavior during sleep and how bladder events and sleep architecture are related. Such insight is imperative for better understanding of the interplay of nocturia and poor sleep to enable personalization of therapies for each individual. Future studies will have improved synchronization to enable assessment of order of bladder and sleep events.