HYPOVENTILATION / LUNG DISEASE
During REM sleep there is a type of paralysis or loss of smooth muscle tone in the arms & legs, throat, lungs & diaphragm.
As a result, unless you have REM behavior disorder it is impossible to:
The result is shallow breathing known as hypoventilation and it causes:
- a drop in oxygen levels AND
- an increase in carbon dioxide levels
Hypoventilation often occurs with the following medical conditions:
- lung disease from COPD, interstitial or pulmonary fibrosis
- obesity or late stages of pregnancy
Even when you are not in REM sleep it is more difficult to take a deep breath while lying down, with or without the above medical conditions, because gravity works against you instead of with you.
Take someone in REM sleep and measure their oxygen levels with a finger pulse oximeter. The levels of someone with normal healthy lungs may drop 3 to 5 %. In lungs that are struggling with any of the above medical conditions the oxygen levels may drop 5 to 10 %, leaving them at oxygen levels that are not heart-friendly for much of the night.