During the most peaceful sleep, some people snore loud, ruining the probabilities of slumber for anyone sharing their bedroom. But even those who do not snore do breathe louder once they nod-off than when they’re awake. Why do people breathe so-loudly when they sleep?
The sound made when you breathe, whether awake or asleep, is caused-by the vibration of air moving through the breathing tube, said Dr. Timothy Morgenthaler, a pulmonologist & sleep medicine specialist at Mayo Clinic in Minnesota.
How loud the breathing sounds depends on how narrow breathing tube is & how fast air travels through it. “You can almost-view it as a musical instrument,” he said.
When you inhale or breathe in, rapid air movement flowing into upper airway, the part of the respiratory system that extends from mouth to larynx & decreases pressure in the entire respiratory tract also called as the airway.
This pressure change will collapse the upper airway which obstructs breathing. A reflex in the upper airway prevents this collapse and keeps pipes open when you are awake.
“Because it is open, the flow through that airway isn’t turbulent, therefore the air moves without a lot of sound,” said Morgenthaler.
But when you are asleep, that reflex is not as strong. The upper airway tends to partially collapse & breathing becomes noisier.
Sleep, especially during Rapid Eye Movement (REM), also results in lower muscle tone around the airway, Morgenthaler said.
In other words, the muscles that support the airway relax, allowing breathing tube to constrict. When the airway gets narrower, the speed of the air moving through-it increases. The air vibrates more & creates more sound.
The narrowness also means that your breaths become quick & shallow. The average person takes around 14 breaths per minute while awake & 15 or 16 while asleep, Morgenthaler said.
“We’re not expecting to go-off & run or chase an animal or gather crops,” he said.
If a person’s breathing tube becomes particularly narrow, they begin to snore. This happens when the airway reaches the diameter of a McDonald’s straw, which is slightly wider than regular straws, Morgenthaler said.
When it is this small, not only does the air inside the airway vibrate, but so do tissues in the area, causing snoring.
If a person’s airway narrows further during sleep, they develop obstructive apnea. The airway can become too narrow that breathing is impossible and person wakes-up to gasp for air.
Even in people without sleep apnea, the airway may narrow this much up to 4 times per hour. When it occurs more often, it-becomes obstructive sleep apnea.
Morgenthaler recommended skipping alcohol at bedtime because it triggers the surrounding muscles to-relax. If that does not help, person may require a machine like Continuous Positive Airway Pressure (CPAP) to keep the airway open during sleep, he said.