From a study reported on WebMD:

May 7, 2009 — Doing certain tongue and facial exercises for 30 minutes daily may ease the severity of obstructive sleep apnea, a Brazilian study shows.

The study included 31 adults with moderate obstructive sleep apnea.

Speech pathologists taught 16 of the patients to do tongue and facial exercises for half an hour daily. Those exercises included brushing the tongue with a toothbrush, putting the tip of the tongue on the soft palate and sliding the tongue backward, pronouncing vowels quickly or continuously, and keeping the tongue in a certain position when eating.

For comparison, the other 15 patients didn’t learn any tongue or facial exercises. They were simply supervised as they sat for half an hour per day, practicing deep breathing through the nose. […]