Obstructive sleep apnea, or OSA syndrome, is a common disorder, and its prevalence may be one of the consequences of America's obesity epidemic. The chronic condition involves problems with breathing during sleep. Obese people have physical and internal characteristics that place them at high risk for developing this disorder. Two proteins, C-reactive protein and leptin, are also prominently featured in obstructive sleep apnea. Through years of research, scientists have learned a lot about how these factors are interconnected. Although treatment of OSA is available, losing weight is also quite effective in reducing the severity of it.
About Obstructive Sleep Apnea
Sleep apnea is a breathing disorder that involves pauses or shallow breaths while you are sleeping. With obstructive sleep apnea, these pauses are caused because your airway has either collapsed or has been blocked. In either case, the ramifications are disrupted sleep, excessive daytime drowsiness and reduced oxygen in your blood. OSA is difficult to diagnose. You may not know you have it, and your routine doctor's visit is not the ideal location to diagnose a sleeping problem. Snoring, choking and gasping for air during sleep are the major signs of sleep apnea. You may also have a headache or dry throat in the morning and have trouble concentrating during the day. The National Heart, Lung and Blood Institute, or NHLBI, reported that between 15 and 20 million people have OSA. The NHLBI also reports that OSA is related to the development of hypertension, heart failure, stroke and ischemic heart disease.
Obesity and Sleep Apnea
Obesity is one of the strongest risk factors for OSA. An article in the journal "Chest" reported, for example, that up to 50 percent of obese men have OSA. The National Sleep Foundation explains that as a person gains weight, especially in the trunk and neck area, the risk of sleep-disordered breathing goes up as a result of compromised respiratory function. A group of Johns Hopkins sleep disorder researchers further elaborated in the February 2008 "Proceedings of the American Thoracic Society" that obesity, especially abdominal obesity, increases the collapsibility of the throat through the mechanics of added weight acting on the tissues of the throat and lung volume. Moreover, internally, obesity may act through proteins called adipokines that act on the central nervous system and possibly affect neuromuscular control of the airway.
C-Reactive Protein
C-reactive protein, or CRP, is produced in your liver and is released when there is inflammation throughout your body. Doctors test for the level of this protein in examining a number of conditions. Both obesity and the effects of sleep apnea can increase c-reactive protein. The Johns Hopkins researchers, for example, explained that obesity induces an inflammatory state because fat tissue contains high amounts of cytokines, which are biochemical messengers that regulate, and may start, inflammatory responses in your body. In addition, the reduced oxygen in the bloodstream that results from OSA, known as hypoxemia, increases CRP levels.
Leptin
Leptin is another protein hormone that is related to obesity and may be implicated in OSA. Leptin is secreted by your fat cells while you sleep. One of the functions of the protein is to bind to receptors in your brain and tell it when you've had enough to eat. It also turns down your appetite and can stimulate more calorie burning. Although obese people tend to have high levels of leptin, they operate in a leptin-resistant state. Reports from the September 2000 "Chest" journal said that obese people with OSA have higher levels of leptin than obese people without OSA. When treated with continuous positive airway pressure, their leptin levels dropped and they became more sensitive to its effects. Moreover, as they become more sensitive to leptin functioning, they lost a great deal of abdominal fat. Scientists now wonder whether treating OSA can reverse leptin resistance and possibly reduce obesity and obesity-induced OSA. In animal studies, leptin has stimulated better breathing, but CRP tends to damper this action.
References
- National Heart, Lung and Blood Institute: What is Sleep Apnea?
- "The Proceedings of the American Thoracic Society"; Obesity and Obstructive Sleep Apnea; Alan R. Schwartz et al.; 2008
- National Sleep Foundation: Obesity and Sleep
- "Chest"; Leptin, Obesity, and Obstructive Sleep Apnea; Paul E. Marik; Sept. 2000
- "American Journal of Respiratory and Critical Care Medicine"; C-reactive Protein, Obstructive Sleep Apnea, and Cognitive Dysfunction in School-aged Children; David Gozal et al.; July 15, 2007
