I want to know what do i have a dry mouth when i wake up?

Many possibilities: It may be as simple as you're doing a lot of mouth breathing at night but other problems could be present. Many diseases can present with a dry mouth or it may be due to medications .It would be important to know if the dryness is only when you wake or other times as well. Any other symptoms? If symptoms do persist or worsen you should seek medical attention.

A new strategy is to use a dentist fabricated tray filled with baking soda-xylitol ‘retainer gel’. It not used nightly teeth often decay rapidly.