What does insomnia have to do with nocturia? It may seem entirely disconnected, but we have found that most people with insomnia also have symptoms of nocturia.
Why is that? In my book, Sound Sleep, Sound Mind, I describe the process at length. Most physicians don't know about the link, but once the process is described to them, they immediately understand. And it effectively shifts a paradigm. They never see insomnia the same again.
Dr. Krakow's lecture on: The Pathophysiology of Nocturia
Your cardiovascular system contains a volume of fluid within the heart and its connecting blood vessels, also called the circulatory system.The kidneys perform a critical function by helping regulate this fluid. If the volume is too high (fluid overload), blood pressure could go too high. If the volume is too low (dehydration), blood pressure could drop. The kidneys respond to either situation by producing more or less urine—urine output—to maintain correct circulatory volume and proper blood pressure.
During sleep, a normal sleeper sleeps through the night without taking in any fluid. What should the kidneys do? If no fluid comes in, the kidneys generate less urine to maintain proper hydration in the bloodstream. In normal sleepers, urine output decreases during sleep to maintain hydration during the night.
The obstruction or resistance to breathing in your upper airway causes your chest to work much harder than during normal breathing. During this struggle for breath, the body exerts more effort to pull air into the lungs, and this causes a large change in pressure inside the chest cavity. This change in pressure has an unexpected side effect that forces more blood to flow towards the heart. The increased blood flow enters the right atrium of the heart, stretching the muscles in this chamber.; Can you guess how these heart muscle cells interpret stretching?
Go to the head of the class if you said, “the heart detects this change as a sign of fluid overload.” The right atrium perceives a direct threat to the body, and it must do something quickly to counteract this signal of a fluid overloaded state. Any guesses as to what it can do? Two gold stars if you said, “it must send a signal to the kidneys to make more urine to relieve the fluid overload.”
In fact, the right atrial heart muscles release a hormone known as “atrial natriuretic peptide (ANP)” into the bloodstream, which is a diuretic—something that makes the kidneys produce more urine.In controlled research studies, patients with SDB produced more ANP and more urine than normal sleepers.
Now, for those whose bladders might be small or sensitive or nervous, can you see how it only takes a small increase in urine output to trigger the need to pee?
As intriguing as the explanation for nocturia sounds, the more amazing fact is that successfully treated SDB rapidly and dramatically reduces ANP and urine output on the first night of treatment. SDB patients who respond to treatment report less or no trips to the bathroom at night. Can you imagine that—not going to the bathroom once, just by treating SDB?
Surely these ideas are something to sleep on…all through the night!