by Rachel Mercik

Created on: January 10, 2009

Obstructive Sleep Apnea (OSA) is a cessation or reduction in airflow through the windpipe during sleep. This reduction and cessation in breathing occurs through a narrowing or complete closing off (obstruction) of the windpipe. While "Apnea" technically refers to the complete cessation of breath (Obstructive Apneas), reduced airflow, known as Hypopnea ("low breath") and Upper Airway Resistance (UARs), through the respiratory channel is also classified as sleep apnea if it elicits a corresponding drop in blood oxygen saturation. Obstructive Sleep Apnea is clinically defined as 5 or more events per hours of sleep of ceased or reduced breathing, referred to respectively as Obstructive Apneas and Obstructive Hypopneas. Moderate and Severe Obstructive Sleep Apnea are defined as 15-30 events and 30 or more events per hour, respectively.

The reduction and cessation of airflow that occurs in sleep apnea causes snoring, hypersomnolence (excessive sleepiness) and/or insomnia, hypertension, headaches, dry mouth, mood and cognitive disturbances. It is possible thats OSA may cause dysregulation of other bodily systems including endocrine and cardiovascular systems. The pathology imposed onto the cardovascular system by OSA can, in its most extreme case, culminate in heart attack and stroke through increased blood pressure and cardiac arrhythmia.

Often, the only clear physical signs of OSA are snoring and witnessed apneic events by the bed partner. Snoring, a classic symptom of OSA, occurs when the sides of the Pharynx vibrate off one another, producing a sound of vibratory quality. While generally perceived as irritating but innocuous, snoring is shown to result in a significant increase in the likelihood of heart attack and stroke.

Disruption of sleep cycles (referred to as sleep architecture) caused by OSA can lead to either excessive sleepiness or, in somewhat fewer cases, insomnia. This loss of sleep quality often leads to an impairment in cognitive function typically experienced as an inability to focus. As our sleep cycles are married intimately to parts of the endocrine system, the body systems controlled by these hormones are inevitably affected, and most noticeably produce depressed or labile mood.

The implications of this disease are far reaching and critical considering that illnesses such as depression, heart and cardiovascular disease have risen over the past few decades. It is possible, through evaluation of these symptoms in the general public, that the actual prevalence of this disease is far greater than suspected. Current statistics place the prevalence of OSA at around 5% of the adult population, while actual prevalence may be safely twice this figure, at 10% of the adult population.

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