Why do we breathe so loudly when we sleep?
During the most peaceful sleep, some people snore obnoxiously loud, ruining the chances of slumber for anyone sharing their bedroom. But even those who don’t snore do breathe louder when 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 and sleep medicine specialist at the Mayo Clinic in Minnesota. How loud the breathing sounds depends on how narrow the breathing tube is and how fast air travels through it. "You can almost view it as a musical instrument," he said.
When you breathe in, rapid air movement flowing into your upper airway — the part of the respiratory system that extends from the mouth to the larynx — decreases pressure in the entire respiratory tract, also known as the airway. This pressure change can collapse the upper airway which obstructs breathing. A reflex in the upper airway prevents this collapse and keeps your pipes open when you’re awake. "Because it's open, the flow through that airway is not turbulent, so the air moves without a lot of sound," Morgenthaler told Live Science. But when you’re asleep, that reflex isn’t as strong. The upper airway tends to partially collapse, and breathing becomes noisier. ...
Sleep, especially during rapid eye movement (REM), also leads to lower muscle tone around the airway, Morgenthaler added. In other words, the muscles that support the airway relax, allowing the breathing tube to constrict. When the airway gets narrower, the velocity of the air moving through it increases. The air vibrates more and creates more sound. ...
