If bad breath, tooth sensitivity or a toothache is plaguing you, perhaps it’s a nighttime habit at the root.

Findings of a recent study back the theory that open-mouth breathing is associated with dental disease such as tooth decay and enamel erosion.

According to a story by Katherine Derla for Tech Times, the University of Otago’s Sir John Walsh Research Institute analyzed the oral pH levels of 10 participants. Alternately, these healthy volunteers were asked to sleep with and without a nose clip that forces them to breathe through the mouth.

The average pH level of those who slept with the nose clips was 6.6, which is slightly acidic compared to the neutral 7 of those who breathed through their noses. The team also found a visible pattern on the pH levels and temperature between morning and evening.

“Intraoral pH decreased slowly over the hours of sleep in all participants, but showed greater falls over a longer period of time when participants were forced to mouth breathe,” said Ph.D. student and study lead author Joanne Choi.

There are times when the pH levels would drop to 3.6 during sleep when the participants were forced to breathe through the mouth. Choi said the dropped rate is below the critical 5.5 threshold when the tooth enamel starts losing its minerals.