During the most peaceful sleep, some people snore uncomfortably loudly and ruin the chances of sleep for anyone who shares their bedroom. But even those who do not snore breathe louder when they nod than when awake. Why do people breathe so loudly when they sleep?
The sound that comes when you breathe – whether you are awake or asleep – is caused by air vibrations moving through the respiratory tract, said Dr. Timothy Morgenthaler, a pulmonologist and sleep specialist at the Mayo Clinic in Minnesota. How loud the breathing sounds depends on how narrow the breathing tube is and how fast air is moving through it. “You can almost see it as a musical instrument,” he said.
When you breathe in, rapid air movement that flows into your upper airway – the part of the airway that extends from the mouth to the larynx – reduces the pressure throughout the airway, also known as the airway. This pressure change can collapse the upper airway, impeding breathing. A reflex in the upper respiratory tract prevents this collapse and keeps your tubes open when you are awake. “Because it is open, the flow through the airways is not turbulent, so the air moves without much sound,” Morgenthaler told WordsSideKick.com. But when you sleep, the reflex is not so strong. The upper respiratory tract tends to partially collapse and breathing becomes noisier.
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Sleep, especially during rapid eye movement (REM), also leads to lower muscle tone around the airways, Morgenthaler added. In other words, the muscles that support the airway relax and allow the breathing tube to contract. As the airways become narrower, the velocity of the air moving through it increases. The air vibrates more and creates more sound.
The crampedness also means that your breathing becomes fast and low. The average person takes approx. 14 breaths per minute while awake and 15 or 16 while sleeping, Morgenthaler said. Even though you breathe more often while you sleep, you actually take in less oxygen and push out less carbon dioxide because your body’s need for ventilation is not as high as when you are awake. “We do not expect to go out and run or hunt an animal or gather crops,” he said.
If a person’s breathing tubes become particularly narrow, they may begin to snore. This usually happens when the airways reach the diameter of a McDonald’s straw, which is slightly wider than regular straws, Morgenthaler said. When it is so small, not only does the air inside the airway vibrate, but also tissues in the area, causing snoring.
If a person’s airways narrow further during sleep, they may develop obstructive sleep apnea. The airway can become so narrow that breathing is impossible and the person wakes up to gasp for air. Even in people without sleep apnea, the airway can narrow as much up to four times an hour. When it occurs more often, it becomes obstructive sleep apnea. Weight loss is often an effective treatment because excess fat around the airways can impede breathing. Morgenthaler also recommended skipping alcohol close to bedtime because it triggers the surrounding muscles to relax. If that doesn’t help, the person may need a machine such as a continuous positive airway pressure (CPAP) to keep the airways open during sleep, he said.
Originally released on WordsSideKick.com.