Here, we examine the literature to determine whether sleeping with the mouth open is a causal factor for snoring and sleep apnoea.


“Open-mouth breathing during sleep is a risk factor for obstructive sleep apnoea (OSA) and is associated with increased disease severity and upper airway collapsibility.” The study which involved 52 patients found that “the more elongated and narrow upper airway during open-mouth breathing may aggravate the collapsibility of the upper airway and, thus, negatively affect OSA severity.”trans

In another study, 385 patients with obstructive sleep apnoea were examined through a questionnaire. Results showed that upper airway symptoms were common, with 61% of patients reporting mouth dryness, 52% with nasal stuffiness, 51% with dryness of the nose, 30% with sneezing, 24% with mucus in the throat, and 17% with a runny nose.

Ohki et al. performed a study to determine the relationship between oral breathing and nasal obstruction in patients with obstructive sleep apnoea. The study involved 30 normal subjects and 20 patients with snoring or sleep apnoea. Researchers found that chronic nasal obstruction and resultant mouth breathing may induce obstructive sleep apnoea.

In a paper entitled, “How does open-mouth breathing influence upper airway anatomy?” Lee et al. tested the hypothesis that open-mouth breathing during sleep may increase the severity of obstructive sleep apnoea. After an analysis of 28 patients, researchers concluded that “open-mouth breathing is associated with reduction of the retropalatal and retroglossal areas, lengthening of the pharynx and shortening of the MP-H in the upper airway.”

After reviewing texts and articles on Medline, The Centre for research disorders in Cincinnati, Ohio concluded that obstructive sleep apnoea, sleep fragmentation, and disturbed sleep often result from nasal obstruction.5 The authors of the paper observed that “since breathing through the nose appears to be the preferred route during sleep, nasal obstruction frequently leads to nocturnal mouth breathing, snoring, and ultimately to OSA.” The paper advised that allergic rhinitis and other upper respiratory disorders should be treated more aggressively.

A Polish study noted that children with sleep respiratory disorders wake up tired, with blocked noses, were breathing through their mouth, tire easily, have concentration problems, are irritated, and demonstrate hyperactivity that may resemble ADHD symptoms. The paper further states that “long-term disease leads to exacerbation of all-systemic symptoms, results in cardiovascular complications, induces developmental inhibition and cognitive dysfunction, and is responsible for school/social failures and reduced life quality.”

In a paper entitled, “The nose and sleep disordered breathing: what we know and what we don’t know,” performed an analysis of medical literature on the subject. The analysis confirmed that “SDB (sleep disordered breathing) can both result from and be worsened by nasal obstruction.” It was stated that “nasal congestion typically results in a switch to oronasal breathing that compromises the airway.” Furthermore, “oral (mouth) breathing in children may lead to the development of facial structural abnormalities associated with SDB.” The paper concluded that the change to mouth breathing that occurs with chronic nasal obstruction is a common pathway for sleep-disordered breathing.

Mouth breathing was also recognised to be a factor in a study to determine the prevalence and association of sleep disorders and school performance. Based on a total of 1,164 completed questionnaires on children aged between 7 and 13 years, it was found that the overall prevalence of snoring was 38.9% with 3.5% habitually snoring. “Allergic symptoms, daytime mouth breathing, shaking the child for apnoea, restless sleep and hyperactivity were significant and independent risk factors and sleep-related symptoms for habitual snoring.”

A study was conducted to determine the risk factors of habitual snoring and symptoms of sleep-disordered breathing. Based on a study of 1030 children aged from 12 to 17 years, it was found that “habitual snorers had significantly more night time symptoms including observed apnoeas, difficulty breathing, restless sleep and mouth breathing during sleep compared to occasional and non-snorers.”

And finally, data from 248 medical charts of mouth-breathing children were analysed to determine the prevalence of obstructive sleep disorders in such children. It was found that 58% of children were primary snorers and 42% had obstructive sleep apnoea. The paper concluded that,  “primary snoring and OSA are frequent findings in mouth breathing children.”

With the scientific findings mentioned above, there is no doubt that mouth breathing is a significant causal factor for snoring and sleep apnoea in both adults and children.

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