Your dry mouth after a night of drinking, assuming you drank alcohol, is from dehydration. Alcoholic beverages have a diuretic effect on the renal system. You may notice that you urinate more while drinking. You can prevent this dry mouth by drinking water in additional to your alcoholic drink. If you stay well hydrated, the dry mouth won't be an issue.
Coincidentally, staying well hydrated with water will also prevent the headaches the next day associated with drinking alcohol. This to, is caused by dehydration. Note that I said to drink water, not soft drinks or tea. These substances also tend to add to the dehydration.
Dry mouth occurs when our mouths do not produce enough saliva. Dry mouth is a very common side effect of drinking alcohol. Symptoms of dry mouth include a dry feeling in the mouth, excessive thirst, dry throat, burning sensation of the tongue, dry tongue, difficulty chewing or swallowing, and bad breath.
Basically, alcohol dehydrates the body. It is a diuretic and causes excess urination. Because of this, it flushes water from the body. This is one of the reasons that people experience a dry mouth following the consumption of alcohol.
To help get rid of dry mouth, it is important to drink plenty of fluids. In addition, sucking on sugar free hard candy and breathing through the nose is also recommended.