Her lips, tongue and mouth appear just fine, but soon after Kelli Rourke wakes up, the burning sets in.
"When I say burning, I don't mean like a scratchy throat or a sore throat. I mean burning," Rourke said.
Rourke has suffered with the non-stop burning for more than five years. She went to a flurry of specialists and was finally diagnosed with burning mouth syndrome, or BMS.
"It started out for me with a burning in the back of the throat up into the upper back of the palate," Rourke said, and then it spread to her tongue.
Doctors diagnose BMS by ruling out everything else, including nerve damage, oral yeast infections and diabetes. Harvard oral surgeon Sook-Bin Woo says it's a tricky condition.
"You can work the patient up extensively with blood work, you can examine the patient very carefully, and you're really going to see nothing," Woo said.
It impacts more women than men. Patients may get a severely dry mouth, but the intense pain is tough to describe. Patients say BMS feels like scalding coffee searing the inside of their mouth, or like actual fire.
"It gets bigger and bigger and bigger through the day," Rourke said. "The only thing that relieves it is eating, drinking or crying for me."
Relief during eating is common, according to Dr. Andres Pinto, who researches the syndrome. He says there are no definitive causes, but there are theories.
"The first one is abnormality in the nerve fibers in the mouth. The other theory is that there is central nervous system abnormality or a brain abnormality in terms of the chemicals in the brain," Pinto said.
There's also no cure. Doctors help patients manage the pain with two drugs typically prescribed for seizures and anxiety.
While BMS never actually goes away, woo says for many patients, the pain dulls an average of seven years after their first symptoms. And not all burning mouth is the same. When doctors can't figure out any trigger for the syndrome, it is called a "primary" condition. However, you can get burning mouth as a side effect of other illnesses.