The Evolutionary Mistake That Chokes Millions of People in Their Sleep Every Night.

The state of the universe.
Aug. 13 2012 7:06 AM

Generation Apnea

The evolutionary mistake that chokes millions of people every night.

Woman sleeping.
As scientists began to understand sleep apnea in more depth, they started to see it as the foundation for serious illnesses affecting the mind.

Courtesy Jupiter Images/Pixland.

The following article is adapted from David K. Randall’s Dreamland: Adventures in the Strange Science of Sleep, out now from W.W. Norton.

This is the tale of how an Australian man with a vacuum cleaner fixed a mistake in evolution.

It begins in the late 1970s. Colin Sullivan is a physician in the respiratory unit at Sydney’s Royal Prince Alfred Hospital. There, he treats patients who have problems breathing. The most common complaint, by far, is snoring. Sullivan knows better than most doctors in his field that snoring is often a sign of a serious disorder known as sleep apnea. The disorder had been identified only about a decade earlier.

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Patients with sleep apnea experience a strange nightly sensation that brings the body disturbingly close to death. First, the throat closes randomly throughout the night, choking off the body’s air supply. This puts in motion a cascade of increasingly bad side effects. As if on a seesaw, the lack of air causes the oxygen levels in the blood to plummet and the blood pressure to jump. The lips and skin start to turn blue. Air may not come into the lungs for up to a minute. And for some patients, the heart stops beating for almost 10 seconds at a time.

Eventually, the brain gets the urgent message that the body is choking. The brain jolts awake, and the body instinctively gasps for air. Yet as soon as the airway is clear, the brain immediately falls back to sleep. That’s when the cycle starts again. It is all so quick that it can happen more than 20 times an hour, all night long, without the sleeper remembering it the next day. Someone lying next to him or her, however, can hear this process at work: When the rhythmic sawing of a snorer’s breath pauses and then becomes a hard ghhack-ghhack-ghhack, it’s most likely the body frantically clearing its airway.  

Sleep apnea was discovered when a group of American physicians noticed that some obese patients complained of overwhelming fatigue and would drift asleep unintentionally. With a literary flourish, they named the condition Pickwickian syndrome after a character who falls asleep standing up in Charles Dickens’s first novel, The Pickwick Papers. Doctors incorrectly attributed the sleepiness to a combination of excess weight and abnormally high levels of carbon dioxide in the blood. It was only later that science understood sleep apnea to be a common breathing disorder caused by the position of the tongue and tissues of the throat. It was then given the name apnea, from the Greek word for breathless.

Sleep apnea was on the frontier of sleep medicine in the late 1970s. Sullivan had recently returned from a fellowship in Toronto, where he spent three years studying the breathing patterns of dogs while they slept. English bulldogs, pugs, and other breeds with pushed-in faces are the only animals besides humans that experience sleep apnea. The years spent working with dogs gave Sullivan an idea. Once back in Sydney, he devised a mask that fit over a dog’s snout. The mask continuously pumped in air from the surrounding room, increasing the air pressure in the throat and preventing it from closing up. Experiments with dogs suggested that the steady flow of air dramatically improved sleep. All Sullivan needed was a human to try it out on.

In June of 1980, he found one. A man walked into the hospital with such a severe case of sleep apnea that Sullivan recommended an immediate tracheotomy. This procedure, which consisted of making a hole in the throat to allow a person to breathe without using the nose or mouth, was one of the few approved treatments for sleep apnea at the time. It required a permanent, quarter-size opening in the neck, however, and was quite painful.

The patient refused the tracheotomy. But he was happy to volunteer as a test patient for Sullivan’s air-pressure machine. Sullivan built a test model that afternoon. He grabbed the engine out of a vacuum cleaner and attached it to a handful of plastic tubes. He then took a diving mask and coated the edges with a silicone sealant that prevented air from leaking out of it. Soon, he had a system that allowed him to pump air through the mask at a controlled pressure. Sullivan found an empty room in the hospital and set up equipment to monitor the patient’s breathing and brain waves, which would tell him what stage of sleep the man was in. The patient was hooked up to the monitors, put on the mask, and fell asleep almost instantly.

He began experiencing sleep apnea within a few minutes. Sullivan then slowly started to increase the pressure in the air flowing through the mask and into the patient’s airway. Suddenly, the apnea stopped. The patient began breathing normally. As Sullivan watched in amazement, the patient instantly went into deep REM sleep—a rare phenomenon suggesting that his brain had been starved of restorative sleep. Sullivan then slowly decreased the pressure of the air flowing through the mask. The apnea returned. Sullivan rapidly went through several cycles of increasing and decreasing the pressure. He found that with the machine’s controls alone, he could effectively turn the patient’s sleep apnea on and off.

The machine worked. The next question was whether its benefits would last all night. Sullivan left the settings on the machine at a level where the patient was free of sleep apnea. Then he waited. For about seven straight hours, the patient was in abnormally intense, deep sleep. When he woke up the next day, he told Sullivan that he felt awake and alert for the first time in years.