Sleep apnea results from a very complex interaction between anatomic, hormonal, neurological, muscular and postural factors. Sleep apnea is a very dangerous disease, because if left untreated it gets progressively worse and has serious health consequences. Certain of the morbid consequences of sleep apnea are a direct result of the obstruction to breathing, some are effects of sleep deprivation, some are hormonal and others result from the changes caused by reduced oxygen getting to the brain.

Excessive daytime sleepiness

The most prevalent and disturbing side effect of sleep apnea is excessive daytime sleepiness (EDS). Patients suffering from EDS are at high risk for automobile accidents, occupational accidents, and poor work performance. Drowsiness was a factor in over 200,000 car crashes, 76,000 injuries and 1,400 deaths in motor vehicle accidents in the year 2000. The odds of having an auto accident are 3 times greater in drowsy drivers. Six states have passed or have legislation pending that a person driving drowsy is subject to reckless homicide felony laws, carrying a prison sentence of 3 - 28 years if found guilty.

Sleep apnea affects the heart

When breathing stops during apnea episodes carbon dioxide levels in the blood increase and oxygen levels drop. This sets off a cascade of physical and chemical events. Nitric oxide causes blood vessels to remain elastic, but sleep apnea causes decreased levels of nitric oxide and thus less elasticity in blood vessel walls.

One recent study showed that the greater the number of nightly apnea episodes a person had, the more likely they were to develop hypertension in the order of four years. Blood pressure fluctuates widely and rapidly in response to episodes of apnea and hypopnea. This is an autonomic nervous system response that controls involuntary muscle activity such as the heart. The transient constriction of blood vessels controlling the heart can lead to sustained hypertension (high blood pressure) and eventual heart damage.

The blood in people with sleep apnea has higher levels of plasminogen. This substance causes the blood to become more viscous or sticky, and is thus more apt to clot and cause strokes. Certain immune factors as well are high in the blood of apnea patients. Immune responses cause inflammation that can damage blood vessels. The white blood cells of apnea patients have an increased number of adhesion molecules. These can bind to the blood vessel linings and also cause inflammation. Inflammation of the blood vessel walls has been implicated in coronary artery disease and heart attacks.

Studies in older people with sleep apnea and excessive daytime sleepiness demonstrate lower test scores for cognitive function. In one study 32% of adult apnea patients also had suffered from depression. Studies of children and adolescents with sleep apnea reported academic underachievement, short attention span, and hyperactivity, all thought to be a result of sleepiness.

The National Commission on Sleep Disorders Research estimates that sleep apnea results in 38,000 cardiovascular deaths each year.


  • Diabetes has been strongly linked to OSA independent of obesity
  • Hypoxia and the “fight or flight” response may be behind the OSA-diabetes link

One of the most troubling diagnosis for patients is to be told they have diabetes.  Diabetes is skyrocketing.  The number of people with diabetes more than doubled between 1980 and 2008. (national, regional, and global trends in fasting plasma glucose and diabetes prevalence since 1980: systematic analysis of health examination surveys and epidemiological studies with 370 country-years and 2-7 million participants.  (Danaei, G et al., The Lancet, Vol 378, No 9785, Pages 31-40, July 2011)

There are certainly many causes linked to this dramatic increase, such as the aging of the world’s populations and the growth of America’s waistline.  Another factor to add to this mix is the side-by-side increase in prevalence of obstructive sleep apnea (OSA).

OSA is strongly linked to Type II diabetes.  This link has been demonstrated even in the absence of obesity. (Obstructive sleep apnea and type 2 diabetes:whose disease is it anyway?  S. Choudhury et al., Practical Diabetes International Vol 28, #4, pp 183-186a, May 2011)

Nader Botros MD, a researcher at Yale University says that although it is not exactly known what the link is between sleep apnea and diabetes, there are some very good clues.  One strong theory is that the lack of oxygen that results from sleep apnea activates the body’s “fight or flight” response which sets in motion a whoe host of other events.  One of these include the productin of hight levels of the hormone cortisol that ultimately leads to insulin resistance and glucose intolerance. (Presented at American Thorasic Society 2007 International Conference on May 21, 2007)  Pre-diabetic conditions, if left untreated, can eventually lead the patient to a later diagnosis of full blown diabetes.

Dr. Botros states that “the impact of diabetes is great.  New approaches are needed to better understand the risk factors for diabetes in order to develop additional preventive strategies.  Understanding the link between sleep-disordered breathing and diabetes may represent one such approach.” (Science Daily, May 2007)

Other factors are also involved in the OSA-diabetes link, including things such as inflammatory mediators of oxidative stress, lepin resistance and hypothalamo-pituitary axis dysregulation.  These effects are tied in to not only the actual nightly hypoxia but also the accompanying sleep fragmentation.  The good news is that effective treatment of OSA leads to a resolution of both of these behaviors. (Effect of continuous positive airway pressure therapy on glucose control, S. Surani et al., World J Diabetes, April 15, 2012, 3(4):65-70.)    


The relationship between sleep and depressive illness is complex – depression may cause sleep problems and sleep problems may cause or contribute to depressive disorders. For some people, symptoms of depression occur before the onset of sleep problems. For others, sleep problems appear first. Sleep problems and depression may also share risk factors and biological features and the two conditions may respond to some of the same treatment strategies. Sleep problems are also associated with more severe depressive illness.


"There is a very high prevalence of OSA in obese individuals and a high prevalence of obesity in patients with OSA.  The pathophysiology of OSA is intimately linked to obesity.  anatomic and functional considerations of the pharyngeal airway, the CNS, central obesity, and leptin likely interact in the development of OSA in obese individuals.  OSA may itself predispose individuals to worsening obesity because of sleep deprivation, daytime somnolence and disrupted metabolism." (Obesity and obstructive sleep apnea, Gami AS, et al., Endocrinol Metab Clin North Am., Dec. 2003, 32(4):869-94.     

Cognitive Dysfunction/Memory Loss

Since people with sleep apnea tend to be sleep deprived, they may suffer from sleeplessness and a wide range of other symptoms such as difficulty concentrating, depression, irritability, sexual dysfunction, learning and memory difficulties, and falling asleep while at work, on the phone, or driving.

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