Sinusitis:

Sinusitis, which causes difficulty swallowing and breathing, can contribute to drooling during sleep. Cold symptoms, which force mouth breathing due to nasal congestion, exacerbate the problem.
Heartburn or esophageal reflux:

Excessive saliva production may result from acidity or GERD, which stimulates stomach acid production, thus increasing saliva.
Allergy or poisoning:

Nasal and food allergies, along with pesticide poisoning, can lead to excessive drooling. Severe cases may pose life-threatening risks, requiring immediate medical attention.
tonsillitis:

Inflammation of the tonsils and throat glands restricts the production of saliva, which accumulates in the back of the throat, contributing to drooling during sleep.
Dental problems:

Gum infections, dental problems, and other dental health problems can lead to increased saliva production.
Congenital oral defects:

Congenital mouth defects, such as an enlarged tongue or swollen lymph nodes, may lead to drooling. Avoiding side sleeping can alleviate this problem.
Side effects of medications:

Some medications, including antidepressants and antidepressants, may increase drooling.
Neurological disorders:

Neurological disorders such as facial paralysis, Parkinson’s disease, Alzheimer’s, stroke, autism, amyotrophic sclerosis, or multiple sclerosis can cause difficulty controlling saliva.