Sleep Apnea

People who suffer from sleep apnea usually snore very loudly but their problem is not just one of snoring. Apnea comes from a Greek word for absence of breath, and refers to the condition where the victim actually stop breathing, often as frequently as every thirty seconds, thus causing interruptions to their sleep. This could be caused by the upper airway being obstructed (obstructive sleep apnea) or by the victim breathing being stopped during sleep and breathing is only resumed when the victim awakens (central sleep apnea). 

Studies in a sleep laboratory proved that John, like up to 8 percent of the adult population, suffered from obstructive sleep apnea. His episodes of loud snoring, alternating with periods of little or no air flow, were typical. When he was in twilight-zone sleep, he was able to overcome the obstruction to air flow in his upper airway. This milder obstruction produced his regular snoring, which measured 42 decibels. However, as he entered deep sleep, the muscles and tissues in his upper airway became more relaxed. The tissues sagged, the soft palate and uvula lost their tone, and the jaw muscles relaxed, allowing his tongue to droop backward.  

All these effects caused narrowing of his airway and, as he became more relaxed, eventually the airway closed off completely. When this happened, the respiratory center in John's brain sent out the signal to his diaphragm to begin the next respiration. The diaphragm contracted, and he began to create a negative pressure within his chest cavity, but it was not enough to overcome the obstruction in his throat. No air moved into his chest. He was, in fact, apneic - that is, breathless. Soon, the level of oxygen in his bloodstream began to fall, and his brain began to panic. His heart rate began to rise, as did his blood pressure, sometimes to alarming levels. Eventually his brain would initiate some changes in posture as a nonspecific reaction to the low levels of oxygen. John would move around in bed, perhaps shaking his head or flailing his arms. Eventually, his brain would wake him up to breathe. After being awakened this way, he would enter a lighter stage of sleep, the muscles in his upper airway would regain some of their tone, and he would be able to move air into his chest. The apneic spell was over. In the sleep lab, these episodes happened to John about three hundred times a night! Basically, when he slept well (that is, when he was in deep sleep), he couldn't breathe. He had a choice: he could either breathe or sleep, but not both together. Only a few seconds after waking up to breathe, he would try to go to sleep again, and the process would repeat itself. No wonder excessive daytime sleepiness is the usual complaint of patients with sleep apnea. Most patients, like John, are unaware of the roller-coaster ride between sleep and wakefulness that they take every single night. Though they may have been in bed and thinking they were asleep for some eight to ten hours, many of them actually sleep only a few minutes each night. Some sleep apneic patients complain of insomnia; they are simply unable to get back to sleep after the frequent awakenings.

Most sleep apneic patients seek medical advice because of the observations and complaints of those who sleep with them. Sleep apnea is usually preceded by several years of snoring, and is uncommon in premenopausal women. The repeated changes in heart rate and blood pressure often lead to chronic hypertension; in fact, if you are a man and you snore, your chance of having high blood pressure doubles. Because the oxygen level in the blood falls regularly during the apneic spell, irregular heart rates are very common and can be disastrous. Mark Twain wrote, "Don't go to sleep - so many people die there." He may have been thinking of sleep apnea, because the drop in oxygen in the blood, the high blood pressure, and the irregular heart beat are thought to be a common cause of sudden death in sleep.

Irritability and depression, caused by chronic sleep deprivation, are commonly seen in sleep apnea. Because people with sleep apnea enter deep sleep for only a few minutes, they essentially live lives of prolonged sleep deprivation. Automatic behavior, like John's, especially soon after awakening, is also common; it simply reflects the chronic, unrefreshing sleep pattern. Impotency, and even incontinence of urine, are also common, as is the reflux of acid from the stomach into the back of the esophagus. This acid is literally sucked up into the chest by the action of the diaphragm creating a negative pressure to try to move air in against the closed upper airway. Sweating at night occurs in almost two-thirds of cases of sleep apnea, and morning headaches are almost universal. Because people with sleep apnea are sleep deprived much of the time, they fall asleep very easily - watching TV, during lectures, or any time stimulation is minimal. 

The rarer form of sleep apnea, called "central sleep apnea," occurs when the brain fails to initiate and coordinate the movements of muscles necessary for respiration. This unusual medical problem has been called "Ondine's curse," after a maiden in a German legend who punished her former lover by causing him to forget to breathe unless he consciously willed it. The poor man had to actively remember to initiate every single breath for the rest of his life. In contrast to obstructive sleep apnea, which is far more common, central sleep apnea does not have the snorting, gurgling respiration that signifies the closure of the airway.