About Sleep Apnea
Definition of Sleep Apnea
Sleep apnea is a disorder in which breathing is disrupted during sleep.
Sleep apnea takes its name from two Greek words, literally meaning "without breath". People with sleep apnea literally stop breathing repeatedly during their sleep, often for a minute or longer, hundreds of times during the night.
What we know as “sleep apnea” is also called obstructive sleep apnea (OSA), apnea-hypopnea syndrome, or simply sleep disordered breathing. It is a common disorder that affects about 4% of the population [1].
Obstructive Sleep Apnea (OSA)
Obstructive sleep apnea is essentially the collapse of the muscles of the upper airway which results in an obstruction in the airway that disrupts breathing. Above the windpipe, from the base of the neck up to the back of the nose, the airway is made up predominantly of about 26 different muscles.
Any of these specific muscles or a combination of them may be the cause obstructive sleep apnea.
When normal breathing stops as a result of obstruction, the brain arouses (usually not to complete consciousness). This causes muscle tone to be returned to the airway, which then opens allowing normal breathing to resume. Sleep returns, muscle tone is lost again and another obstruction occurs triggering another arousal. This cycle can continue all night.
Central Sleep Apnea
Not all sleep apnea is obstructive. Another, less common, form of the disorder is called Central Sleep Apnea or Cheyne-Stokes Breathing. This is a neurological condition in which the trigger for breathing is either not received or not acted upon by the brain, resulting in the cessation of normal breathing. It is also possible to have a combination of central and obstructive forms of the disorder, known as Mixed Sleep Apnea.
How Sleep Apnea Does Damage
As sleep apnea appears to be related to the loss of muscle tone, age is a factor. That said, sleep apnea can be diagnosed at any age and has been diagnosed in babies and infants – tenuous links have recently been drawn between sleep apnea and SIDS, the theory being that the reflex to arouse is not well developed in babies, so they do not respond when the airway collapses.
However, the structure of the airway is also important as it determines the starting position of the walls of the airway; or to put it another way, how far the muscles can relax before they cause an obstruction. Weight is yet another factor. Obesity results in deposits of fat around the neck which can push down on the airway, exacerbating the effects of the loss of muscle tone.
The result of the sleep apnea cycle is (unsurprisingly) poor sleep quality, typically resulting in daytime sleepiness. However, during the night the sleep apnea sufferer may also have significant blood oxygen desaturation.
When this occurs the cells in the body, which are used to richly oxygenated blood, are not able to function as well as they do with normally oxygenated blood. Over time, this nocturnal blood oxygen desaturation combined with the frequent disruptions to normal sleep can cause damage to the organ systems of the body.
A range of health conditions are linked to sleep apnea, possibly as a result of the damage caused over time by blood oxygen desaturation: high blood pressure, heart attack, stroke, obesity, diabetes, heart failure, irregular heartbeats and an increased risk of work-related or driving accidents. Sleep apnea has also been linked to emotional and mental health conditions, cognitive dysfunction, relationship problems and depression.
Diagnosis of Sleep Apnea
The majority of sleep apnea cases are undiagnosed. The reason for the low rate of diagnosis is that snoring, which is the most common symptom of airway collapse, is not considered to be an indicator of a potentially serious medical condition.
The sleep apnea sufferer is also used to feeling sleepy or not being able to perform as well as they did when they were younger, and may not automatically assume that anything is “medically” wrong.
Often it is the partner of the sufferer that prompts medical attention. That said, the medical community is becoming increasingly aware of the impact to overall health and wellbeing which results from conditions such as sleep apnea and diagnosis rates are increasing.
The normal treatment pathway is that the sufferer reports symptoms of sleepiness to a family doctor as a first step. A battery of tests is usually conducted which may or may not show some areas of concern, such as high blood pressure or diabetes. Treatment may be started to address anything reported by the tests.
Often, nothing of concern is noticed during the initial tests and the doctor may then order a sleep study. A sleep study, also called polysomnography (PSG for short) involves the recording of information about brain, heart and breathing function during sleep.
PSGs can be carried out in an overnight sleep clinic or can be conducted in your home. The results of the PSG are studied by technicians and specialist doctors who can then determine if a diagnosis of sleep apnea is indicated.
The Apnea-Hypopnea Index (AHI)
The PSG will determine something called the Apnea-Hypopnea Index, which is the number of apneas and hypopneas[2] which occur per hour during the sleep study. An AHI of less than 5 normally results in a diagnosis of the condition which is not necessary to treat. An AHI between 5 and 15 is classified as mild, between 15 and 30 is considered moderate, and over 30 is considered severe. There is no fixed upper limit to the AHI, although AHIs of over 60 are rare.
Treatments for Sleep Apnea
Treatment options depend upon the individual and the nature of the condition, but typical treatment options are as follows:
AHI <5 No diagnosis of sleep apnea, however the doctor may recommend weight reduction, smoking cessation, exercise and improved diet to control the onset of the disorder
AHI 5 to 15 Mild sleep apnea.Lifestyle factors, CPAP, mandibular splint
AHI 15 to 30 Moderate sleep apnea.Lifestyle factors, CPAP
AHI 30+ Severe sleep apnea.Lifestyle factors, CPAP
Continuous Positive Airway Pressure (CPAP) therapy
CPAP therapy involves an airflow generator attached to a mask which is worn over the nose during sleep. This pressurised air holds open the airway and prevents the relaxed muscles collapsing into the airway and disrupting breathing
Mandibular Advancement Splints look and feel like mouthguards that are worn during some sports. They function by holding the jaw in a forward position to help keep the tongue from falling back into the throat during sleep. These splints work best with mild sleep apnea and are particularly effective if the tongue is the site of the airway collapse.
Surgery has been used in the past to try to provide more tolerance in the airway during collapse, to remove unnecessary tissue and also to add stiffness to the muscles of the airway. Surgery is not normally a treatment of choice for sleep apnea, being quite painful, having low rates of success and being risky. That said, new surgical techniques and approaches are continually evolving and may be more necessary in some individuals.
Herbal and other alternative remedies, such as breathing techniques and exercises, sleep positioning devices and pressure point therapy may work for some people, but have not been scientifically supported by the medical and sleep research fraternities.
Drug treatment is not normally indicated and there is no pill that cures or treats sleep apnea. Again, some individuals may have specific factors which indicate the need for drug treatment of aspects of the disorder and research in this area continues.