Obstructive Sleep Apnea (OSA)

Sleep apnea is a sleep disorder in which breathing pauses during sleep. With obstructive sleep apnea (OSA), breathing temporarily stops (apnea) due to a constricted airway, in contrast to central sleep apnea, where the brain temporarily fails to send signals to the muscles that control breathing.^[1] After breathing pauses, the brain triggers a sudden gasp to resume breathing. The stop-start cycle of breathing repeats throughout the night, preventing the body from falling into a deep sleep and reducing oxygen levels. Since OSA tends to take a severe toll on the mind and body, treatment to keep the airway open during sleep is critical to avoiding adverse health consequences.

Snoring is one of the main signs of sleep apnea, which is interrupted by periods of silence when breathing stops. People with sleep apnea are often unaware of their snoring but may be aware of waking up gasping for breath intermittently throughout the night. The sleep partners of people with OSA are usually quite aware of the signs, since the snoring, gasping, and choking can be quite loud. Although snoring is common in people with OSA, it is important to note both that snoring is not an indicator of OSA by itself — snorers do not necessarily have OSA — and also that people can have OSA without being snorers.

OSA can cause any of the following symptoms:^[1][2]

• Waking up feeling tired or exhausted in spite of going to bed on time
• Extreme daytime sleepiness
• Feeling irritable, depressed, or anxious
• Problems with concentration and focus
• Impaired memory
• Dry mouth
• Frequently waking up during the night to urinate
• High blood pressure
• Morning headaches
• Chronic eyelid inflammation

When OSA is suspected, a physician will first inquire about any history of snoring or typical symptoms such as daytime sleepiness. A medical exam of the neck, mouth, and throat will also be performed to examine the airway. Screening tools such as the STOP-Bang questionnaire and the Epworth Sleepiness Scale (ESS) may be used to determine a person’s risk for OSA.^[3] The only way to confirm a diagnosis of OSA is by conducting a polysomnography (sleep study) test, which measures sleep stages and cycles.^[4]

In addition to weight loss, continuous positive airway pressure (CPAP) therapy is considered the gold-standard therapy for OSA.^[5] CPAP therapy works by creating positive pressure in the airway, preventing it from closing during sleep. A mask is worn over the nose or nose and mouth, which is connected via a hose to a machine that provides continuous positive airflow, preventing the airway from closing while sleeping.^[6] Although generally the most effective treatment, people often find CPAP therapy uncomfortable and difficult to adhere to.^[7] Oral devices such as mandibular advancement devices (MADs) that alter the position of the jaw while sleeping to help keep the airway open are an alternative treatment for people with mild to moderate sleep apnea who are poor candidates for CPAP or failed to respond to CPAP.^[8] The drawback to MADs is that they tend to be less effective than CPAP overall, with one 1 out of 3 patients showing no improvements in their condition.^[9]

Antioxidants have been studied for OSA, since it is associated with increased levels of oxidative stress. Although oxidative stress is reduced by CPAP therapy^[10], the relationship between antioxidant levels in the body and OSA isn’t well-understood.^[11]. One small cohort study noted an improvement in OSA symptoms after 8 weeks vitamin D supplementation in participants with mild OSA and low vitamin D levels at the start of the trial.^[12] This particular study lacked appropriate blinding and controls to yield conclusive results, however, and studies examining associations between vitamin D levels and OSA have reported inconsistent results.^[13] Nitrate supplements have also been studied for OSA, and were found in one randomized crossover trial to reduce the OSA-induced increase in early-morning blood pressure.^[14]

Since obesity increases the chances of having OSA, various diets have been studied for their effectiveness in treating the disease, either as stand-alone interventions or as part of broader healthy lifestyle changes that include exercise and sleep hygiene. Healthy diets^[15] — particularly those with anti-inflammatory potential^[16] — have been associated with less OSA risk in observational studies. Specific diet interventions have also shown positive effects in people with OSA. A randomized controlled trial testing a paleo-style diet intervention found that sleep apnea symptoms were reduced by the paleo diet compared to a control low-fat diet, but only in participants on the paleo diet who lost significant amounts of body weight.^[17] A randomized controlled trial also found that the Mediterranean diet improved OSA symptoms, regardless of weight loss, when it was combined with a lifestyle intervention that included exercise and healthy sleeping habits.^[18]

Surgery is an alternative treatment for people with OSA who have either failed to respond to CPAP therapy or are unable to tolerate it. Surgical techniques used can vary based on the physiology of the individual being treated, but are generally performed to remove excess tissue or remodel the upper airway to prevent obstructions.^[19]

Lifestyle interventions may also be effective treatments for OSA, since obesity is a significant risk factor.^[20] One 89-participant randomized controlled trial comparing a diet and lifestyle intervention to standard CPAP therapy in men with moderate to severe OSA and overweight or obesity found that the diet/lifestyle intervention eliminated the need for CPAP therapy in over 60% of the participants. Remarkably, 29% of the participants in the lifestyle intervention group achieved complete OSA remission.^[21]

Reducing alcohol consumption may help to improve sleep apnea symptoms, since higher levels of alcohol consumption are an OSA risk factor.^[22]

Exercise may also improve OSA symptoms in people with sleep apnea by reducing the accumulation of fluid in tissues surrounding the upper airway at night, which helps to reduce constriction.^[23]

OSA is caused by a temporarily constricted airway, which interrupts breathing. During sleep, muscles become more relaxed, including those in the throat that help to keep the airway open. Although more relaxed, muscles in the throat are normally able to keep the airway open during sleep. In people with OSA, the airway is more constricted and becomes temporarily blocked, preventing breathing.^[24] The blockage can be caused by several factors, including individual physiology — some people have naturally narrow airways due to a large tongue, or large tonsils and adenoids. Having a large neck circumference also increases the risk for OSA^[25], as does obesity.^[26] Chronic inflammation may also play a causal role in developing OSA, but the mechanisms are not well-understood. One observational study found that increased inflammation during childhood may be a possible link between visceral body fat levels and developing OSA in adolescents.^[27]