Why You Have To Pee At 3AM

Jessica is a 55-year-old woman who is seeing a urologist for her “overactive” bladder. She wakes up 3-4 times each night to urinate, and also has too many urges to go during the day. She came to see me about her snoring problem. A sleep study found that she stopped breathing 35 times every hour. After using a dental device, not only did her snoring go away, she also slept much better and she only woke up once every night to urinate.

So what’s the link between obstructive sleep apnea and nighttime urination? Why did Jessica’s bathroom trip frequency improve? 

There’s a well known hormone called atrial natriuretic peptide (ANP) that’s made by the heart in response to fluid overload. If you have heart failure, too much blood remaining in your heart along with returning blood will tend to stretch the atrial chambers, leading to ANP production. ANP goes to your kidneys to promote urine production, leading to less blood volume. 

Similarly, people with obstructive sleep apnea will repeatedly inhale against a closed throat, creating repeated vacuum effects that also stretch your heart muscles, making it think that there’s too much fluid. 

During sleep, you’ll go through 4 to 5 sleep cycles about 90 to 120 minutes long. In the first 90 minutes, you’ll go into deep (slow wave) sleep, but with each successive sleep cycle, you’ll have shorter periods of deep sleep and longer periods of REM sleep. Stage REM is when you are dreaming, but also when your muscles are completely relaxed. As your tendency for sleepiness goes down and your circadian rhythm starts to promote wakefulness, around 3AM is when everything comes together, making you more likely to wake up due to an obstructive event, and thinking you have to urinate. (I talk more about sleep cycles and why some people wake up too early on this post.)

A number of studies have shown that obstructive sleep apnea and nighttime bathroom trips (nocturia) go hand in hand. One study found that the more times you go to the bathroom, the more likely it is that you may have obstructive sleep apnea.1 In a study of 138 patients, 48% were found to have pathological nocturia. Of note, women had more problems than men (60% vs. 40%). In men with benign prostatic hypertrophy (BPH), about 58% were at high risk for obstructive sleep apnea based on the Berlin sleep questionnaire.2 In a group of 21 women with nocturia and 16 who also had daytime overactive bladder, 81% in both groups had significant obstructive sleep apnea based on home sleep testing.3

In a retrospective study of over 1000 patients, nocturia (84.8% accurate) was just as good as snoring (82.6% accurate) in predicting the presence of obstructive sleep apnea, based on sleep studies.4 Another study found that treating nocturia with CPAP in patients with OSA significantly lowered that average number of awakenings (from 2.5 to 0.7 times per night). 5

Pressman and colleagues found that in 80 patients with nocturia, 79% of awakenings at night were due to obstructed breathing, rather than from a distended bladder.6 Furthermore, going to the bathroom more than two times every night was found to raise your risk of dying overall by 50% in men and 30% in women. Postmenopausal women (ages 50 to 64) with two or more bathroom trips had a 94% increased risk of dying.7 You may think that getting up to go to the bathroom only increases your risk of falls—which actually has been proven.8 However, if you take into consideration that having untreated obstructive sleep apnea can significantly raise your risk of dying due to heart attack, stroke, cancer or car accidents, then these frightening results are not surprising.

Do you wake up to go to the bathroom? If so, how often? If you were treated for obstructive sleep apnea, did your nighttime bathroom trips improve?


References 

  1. Kaynak H, Kaynak D, Oztura I. Does frequency of nocturnal urination reflect the severity of sleep-disordered breathing? J Sleep Res. 2004;13(2):173–176. 
  2. Tandeter H, Gendler S, Dreiher J, Tarasiuk A. Nocturic episodes in patients with benign prostatic enlargement may suggest the presence of obstructive sleep apnea. J Am Board Fam Med. 2011;24(2):146–151. 
  3. Lowenstein L, Kenton K, Brubaker L, Pillar G, Undevia N, Mueller ER, FitzGerald MP. The relationship between obstructive sleep apnea, nocturia, and daytime overactive bladder syndrome in women. Am J Obstet Gynecol. 2008;198(5):598.e1–5.
  4. Romero E, Krakow B, Haynes P, Ulibarri V. Nocturia and snoring: predictive symptoms for obstructive sleep apnea. Sleep Breath. 2010;14(4):337–343. 
  5. Margel D, Shochat T, Getzler O, Livne PM, Pillar G. Continuous positive airway pressure reduces nocturia in patients with obstructive sleep apnea. Urology. 2006;67(5):974–977. doi:10.1016/j.urology.2005.11.054.
  6. Pressman MR, Figueroa WG, Kendrick-Mohamed J, Greenspon LW, Peterson DD. Nocturia. A rarely recognized symptom of sleep apnea and other occult sleep disorders. Arch Intern Med. 1996;156(5):545–550.
  7. Kupelian V, Fitzgerald MP, Kaplan SA, Norgaard JP, Chiu GR, Rosen RC. Association of nocturia and mortality: results from the Third National Health and Nutrition Examination Survey. J Urol. 2011;185(2):571–577. 
  8. Asplund. Mortality in the elderly in relation to nocturnal micturition. BJU International. 1999;84(3):297–301. 

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2 thoughts on “Why You Have To Pee At 3AM

  1. I read elsewhere that ANP is an anti-diuretic. Yet your post describes it as promoting urine production (which is what a diuretic would do, not an anti-diuretic).

    What I read was that during healthy sleep, the body produces ANP in an attempt to maintain sleep–by shutting down urine production. The body fights to maintain sleep, and ANP is how it does this. I’ve read this repeatedly from different sources.

    I told my father, who obviously has OSA (has not been diagnosed and is in denial) that the reason he makes four bathroom trips a night is because his body is NOT producing ANP, and thus, his kidneys are in crank-out mode.

  2. Kellsi,

    What you’re reading is mistaken. Take a look at the Wikipedia article on ANP. It’s a diuretic, increasing sodium excretion, and inhibiting angiotensin and aldosterone, which are anti-diuretics, holding onto sodium. This is why nighttime urination typically improves after CPAP treatment for obstructive sleep apnea. The word natriuresis means excreting sodium.