When we are younger, the body produces an anti-diuretic hormone that enables us to retain fluid during the night. As a result, the body produces less, but concentrated, urine. Therefore, there is little need to wake up during the night.
However, as we age, the body produces less of the anti-diuretic hormone. Consequently, the body starts producing more urine during the night. As a result, we end up having to void during the night. Nocturia is waking up at night to void, with each voiding episode preceded and followed by sleep.
At the same time, age related changes in the amplitude of circadian rhythms may also lead to nocturia.
In addition, fluids may build up during the day, often in the legs. Then, when you lie down to sleep with your legs elevated, the fluid finds its way to the bladder and cause nocturia.
Also, as we grow older the bladder tends to lose holding capacity. In fact, the bladder capacity of men, as they age, goes down from 256 mL to 152mL, while the bladder capacity of women, as they age, goes down from 202 mL to 111 mL. And the reduced bladder capacity may cause nocturia.
Nocturia becomes more common as we get older. In fact, urological surveys have found few young adults have nocturia. On the other hand, 50% of people in their 60s and nearly 80% of older age groups have nocturia.
A study in Austria found 3% of adults younger than 30, 30% of adults aged 60-69, and 40% of adults aged 70 and older have nocturia. Yet, another study showed 62% of men aged 55-74 and 80% of men over 75 have nocturia, with similar numbers for women.
A study has shown that 7% of the population with nocturia has nocturnal polyuria, 57% have decreased functional bladder capacity, and 36% a combination of both. Nocturnal polyuria is nighttime urine production that is greater than 20% of total daily volume for younger adults and that is greater than 33% of total daily volume for older adults. As a result, people with nocturnal polyuria get up more frequently during the night.
Surveys have found nocturia causes sleep disruption with a majority of older adults saying needing to void wakes them up. However, it’s possible that age related changes in sleep depth and continuity makes it more likely that the older adults may be waking up because of decreased sleep depth and continuity and then decide to void.
Most of all, findings suggest that rather than waking up due to a filled bladder, people first wake up due to a primary sleep disturbance and then proceed to nighttime voiding.
Paradoxically, people wake up regularly during the night because people sleep in cycles. And these cycles are generally about 90 minutes to two hours long, though we tend to go through shorter cycles more as we get older, and aren’t able to sustain deep sleep as much as we used to. But mostly when we wake up after a cycle, we will roll over or shuffle or go to the bathroom and then try to go back to sleep again. So because of the sleep cycles, we actually wake up several times a night. For some people, it’s not the waking up that’s the problem, it’s getting back to sleep.
So to minimize the trips to the bathroom:
- Cut back on alcohol in the evening
- No caffeine in the evening
- Avoid drinking liquids 2-3 hours before bedtime
- Void two times prior to sleeping to really empty your bladder
- Elevate legs or use compression stocking to reduce fluids built up in the legs
Most of all, don’t let nocturia prevent you from getting your 7 to 8 hours of sleep. Which would be bad (see infographic).