May
18
2011
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WHY YOU CAN’T STAY AWAKE: THE PHYSICAL CAUSES OF SLEEP APNEA

WHY YOU CAN’T STAY AWAKE: THE PHYSICAL CAUSES OF SLEEP APNEA
What is the physical process that leads to sleep apnea? Almost always apneic episodes result from an obstruction of the pharynx occurring somewhere between the nose and the epiglottis— the membrane that prevents food from going down the wrong “pipe.” The upper airway, from the mouth and nose to the lungs, is not just a hollow tube through which breath moves: the coordinated activity of a number of muscles is required if this airway is to work efficiently and effectively. As we breathe in, these muscles must contract, in synchronized fashion, to pull the passage open: this muscle contraction, as well as our instinct to breathe, is controlled by the central respiratory drive in the brain. Like many bodily structures, the upper airway is pretty delicate: it doesn’t take a very big difference in air pressure between the atmosphere and the inside of the throat to cause the passageway to collapse. The muscles must therefore work continually to keep the tube open.
As we have seen, a number of factors—among them drugs, alcohol, and, to some extent, sleep itself—can suppress the central respiratory drive, especially during slow-wave sleep and the REM phase. Alcohol is a particular threat; not only does it suppress the breathing drive, it also relaxes the throat muscles, reducing their ability to keep the airway open. What’s more, alcohol weakens the mechanism that helps us wake up quickly, thus adding to the time it takes to become aroused enough to make the conscious effort needed to breathe. I tell all patients with apnea that use of alcohol, other than perhaps a very small quantity (less than an ounce), is inadvisable. If they must drink, I ask them to do so no later than four to six hours before bedtime.
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What is the physical process that leads to sleep apnea? Almost always apneic episodes result from an obstruction of the pharynx occurring somewhere between the nose and the epiglottis— the membrane that prevents food from going down the wrong “pipe.” The upper airway, from the mouth and nose to the lungs, is not just a hollow tube through which breath moves: the coordinated activity of a number of muscles is required if this airway is to work efficiently and effectively. As we breathe in, these muscles must contract, in synchronized fashion, to pull the passage open: this muscle contraction, as well as our instinct to breathe, is controlled by the central respiratory drive in the brain. Like many bodily structures, the upper airway is pretty delicate: it doesn’t take a very big difference in air pressure between the atmosphere and the inside of the throat to cause the passageway to collapse. The muscles must therefore work continually to keep the tube open.
As we have seen, a number of factors—among them drugs, alcohol, and, to some extent, sleep itself—can suppress the central respiratory drive, especially during slow-wave sleep and the REM phase. Alcohol is a particular threat; not only does it suppress the breathing drive, it also relaxes the throat muscles, reducing their ability to keep the airway open. What’s more, alcohol weakens the mechanism that helps us wake up quickly, thus adding to the time it takes to become aroused enough to make the conscious effort needed to breathe. I tell all patients with apnea that use of alcohol, other than perhaps a very small quantity (less than an ounce), is inadvisable. If they must drink, I ask them to do so no later than four to six hours before bedtime.
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Written by admin in: Anti Depressants-Sleeping Aid |

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