Sleep apnea

Sleep apnea, also spelled sleep apnoea, is a sleep disorder in which pauses in breathing or periods of shallow breathing during sleep occur more often than normal.[1] Each pause can last for a few seconds to a few minutes and they happen many times a night.[1] In the most common form, this follows loud snoring.[2] There may be a choking or snorting sound as breathing resumes.[1] Because the disorder disrupts normal sleep, those affected may experience sleepiness or feel tired during the day.[1] In children, it may cause hyperactivity or problems in school.[2]

Sleep apnea
Other namesSleep apnoea, sleep apnea syndrome
Obstructive sleep apnea
SpecialtyOtorhinolaryngology, sleep medicine
SymptomsPauses breathing or periods of shallow breathing during sleep, snoring, tired during the day[1][2]
ComplicationsHeart attack, stroke, diabetes, heart failure, irregular heartbeat, obesity, motor vehicle collisions,[1] Alzheimer's disease,[3][4] and premature death[5]
Usual onsetVaries; 50% of women age 20-70[6]
TypesObstructive sleep apnea (OSA), central sleep apnea (CSA), mixed sleep apnea[1]
Risk factorsOverweight, family history, allergies, enlarged tonsils[7]
Diagnostic methodOvernight sleep study[8]
TreatmentLifestyle changes, mouthpieces, breathing devices, surgery[1]
Frequency~ 1 in every 10 people,[4][9] 2:1 ratio of men to women, aging and obesity higher risk [6]

Sleep apnea may be either obstructive sleep apnea (OSA), in which breathing is interrupted by a blockage of air flow, central sleep apnea (CSA), in which regular unconscious breath simply stops, or a combination of the two.[1] OSA is the most common form.[1] OSA has four key contributors; these include “anatomical compromises" like a narrow, crowded, or collapsible upper airway. Or “non-anatomical” ones like an ineffective pharyngeal dilator muscle function during sleep, airway narrowing during sleep, or unstable control of breathing (high loop gain).[10] Other risk factors include being overweight, a family history of the condition, allergies, and enlarged tonsils.[7] Some people with sleep apnea are unaware they have the condition.[1] In many cases it is first observed by a family member.[1] Sleep apnea is often diagnosed with an overnight sleep study.[8] For a diagnosis of sleep apnea, more than five episodes per hour must occur.[11]

In central sleep apnea (CSA), the basic neurological controls for breathing rate malfunction and fail to give the signal to inhale, causing the individual to miss one or more cycles of breathing. If the pause in breathing is long enough, the percentage of oxygen in the circulation will drop to a lower than normal level (hypoxaemia) and the concentration of carbon dioxide will build to a higher than normal level (hypercapnia).[12] In turn, these conditions of hypoxia and hypercapnia will trigger additional effects on the body. Brain cells need constant oxygen to live, and if the level of blood oxygen goes low enough for long enough, the consequences of brain damage and even death will occur. However, central sleep apnea is more often a chronic condition that causes much milder effects than sudden death. The exact effects of the condition will depend on how severe the apnea is and on the individual characteristics of the person having the apnea.

Treatment may include lifestyle changes, mouthpieces, breathing devices, and surgery.[1] Lifestyle changes may include avoiding alcohol, losing weight, stopping smoking, and sleeping on one's side.[13] Breathing devices include the use of a CPAP machine.[13] With proper use, CPAP improves outcomes.[14] Evidence suggests that CPAP may improve sensitivity to insulin, blood pressure, and sleepiness.[15][16][17] Long term compliance, however, is an issue with more than half of people not appropriately using the device.[14][18] In 2017, only 15% of potential patients in developed countries used CPAP machines, while in developing countries well under 1% of potential patients used CPAP.[19] Without treatment, sleep apnea may increase the risk of heart attack, stroke, diabetes, heart failure, irregular heartbeat, obesity, and motor vehicle collisions.[1]

Alzheimer's Disease and severe obstructive sleep apnea are connected[3] because there is an increase in the protein beta-amyloid as well as white-matter damage. These are the main indicators of Alzheimer's, which in this case comes from the lack of proper rest or poorer sleep efficiency resulting in neurodegeneration.[4] Having sleep apnea in mid-life brings a higher likelihood of developing Alzheimer's in older age, and if one has Alzheimer's then one is also more likely to have sleep apnea.[9] This is demonstrated by cases of sleep apnea even being misdiagnosed as dementia.[20] With the use of treatment through CPAP, there is a reversible risk factor in terms of the amyloid proteins. This usually restores brain structure and cognitive impairment.[21][22]

OSA is a common sleep disorder. A large analysis in 2019 of the estimated prevalence of OSA found that OSA affects 936 million—1 billion people between the ages of 30-69 globally, or roughly every 1 in 10 people, and up to 30% of the elderly.[23] Sleep apnea is somewhat more common in men than women, roughly a 2:1 ratio of men to women, and in general more people are likely to have it with older age and obesity.[6]