Reason why Chronic Cough, Phlegm, Dry Mouth and Sore Throat.
Because people tend to sleep with mouth open during shallow sleep.
If people sleep with lips open causes
The reason is that following conditions:-
Entrance of esophagus is closing when mouth is opening.
Dry mouth, sore throat as well as bad breath arise from the evaporation of saliva through opening mouth. The reason of halitosis (bad breath) is bacteria that come with intake air by mouth breathing and become attached to throat.
Saliva can't go into esophagus due to closing the entrance of esophagus by opening mouth.
Note: View from top Patient who is opening mouth due to camera with cable in mouth.
And then dam of saliva flow into lung (windpipe), that's reason why people sometime choke in asleep and cough and phlegm occur.
When mouth is open
The above conditions bring about the worst-case scenario to be pneumonia when saliva contents bacteria and flow with mouth breathing.
Once mouth is closing within 14 days naturally in asleep, after strengthening lip closure strength.
The entrance of esophagus is opened involuntary by closing mouth.
Saliva can go into esophagus safely without flowing in windpipe (lung).
When mouth is closed
Closed mouth maintain saliva in mouth and throat, so no chance to have dry mouth, sore throat, bad breath, dry lips and mouth ulcers as well.
Moreover, airway is widening and secure involuntary to prevent snore and sleep apnea.
*There are individual differences in effect.