This can occur due to malocclusion of teeth or due to psychological stress. In
adults sleep talking could be associated with stress, anxiety or other
sleep disorders. Sleep deprivation and stress are known to aggravate these symptoms. As the symptoms are interfering with your sleep schedules consult your doctor.
In the meantime, follow good sleep hygiene measures like going to bed at the same time, waking up at the same time, avoidance of alcohol, smoking and caffeinated beverages.