2. Medication Side Effects
Certain medications, including sedatives, antipsychotic drugs, and some antibiotics, can lead to drooling as a side effect. Interestingly enough, some NSAIDs (aka ibuprofen) can also lead to drooling while sleeping. This is not a reason to stop taking your prescription medications, however, if it is bothering you, speak to your doctor about it. They can maybe prescribe you something else or change your dose so that this stops happening.