During the night whilst asleep my mouth is full of phlegm(mucus) even though i have no cold and do not cough. Do l have an infection? lf not, what explains that.

Hello and welcome to EmpowHer,
Since your postnasal drip is not related to having a cold or sinus infection it may be the following:
--Deviated septum (abnormal placement of the wall that separates the two nostrils) or another anatomical problem that affects the sinuses
--Changing weather fronts, cold temperatures, or excess dryness in the air
--Certain foods (for example, spicy foods may trigger mucus flow)
--Fumes from chemicals, perfumes, cleaning products, smoke, or other irritants
--Certain medications (including some birth control pills and blood pressure medications)

If the problem persists you will be to see a doctor to determine the cause and receive the proper treatment is necessary.
I hope that helps.
Faith