Sleep apnea in the presumably health working population – revisited - Lavie (2002)
Key Points
Obstructive sleep apnea is associated with and might cause hypertension
Mouth breathing causes sleep apnea, suggesting that is also contributes to hypertension
Receptors in the nose might be critical for maintaining rhythmic breathing during sleep
The Breathing Diabetic Summary
This is another article about sleep from the same author who gave us one of the best quotes ever on nose breathing and sleep (see that note here). This paper was more of a review, where he looked at how some results he got back in 1983 have since been confirmed and extended.
The first thing to note is that sleep apnea is much more prevalent than one might think. Symptoms like excessive daytime sleepiness, headaches, and hypertension might all be the result of undiagnosed sleep apnea. From that list, I really want to focus on hypertension.
Lavie states that the discovery of link between sleep apnea and hypertension might be as important as the discovery of sleep apnea itself. It turns out that sleep apnea is highly correlated with hypertension. For example, one study showed that the prevalence of sleep apnea was 20 times greater in patients with essential hypertension than in presumably healthy workers. What’s more, animal studies suggest that sleep apnea causes hypertension. In one study, sleep apnea was mechanically forced upon dogs, and the dogs developed hypertension shortly thereafter. The hypertension went away shortly after the sleep apnea stimulus was removed.
Why is this so important? Several reasons. First, hypertension is greater in diabetics than in non-diabetics. Moreover, we know from Fitzpatrick et al. (2003) that mouth breathing leads to obstructive sleep apnea. So, mouth breathing causes sleep apnea, which then causes hypertension. Finally, we know from several studies (for example, here, here, or here) that slow breathing reduces blood pressure in hypertension. All together, these results suggest that slow breathing, combined with taping at night (Principle 1 and Principle 2), has the potential to greatly reduce our risk of hypertension as diabetics.
Lastly, this review also highlighted the importance of nasal breathing during sleep. One really interesting study showed that, when the nasal passages if subjects were anesthetized, there were four times as many breathing events during sleep as when they were not. This suggested that receptors within the nose are responsible for maintaining proper rhythmic breathing during sleep. This implies that the nose is the preferred route for breathing during sleep, which has also been found in other studies.
Journal Reference:
Lavie, P., (2002) Sleep apnea in the presumably health working population – revisited, Sleep, 25 (4), 380 – 387, https://doi.org/10.1093/sleep/25.4.380.