Do you have sleep apnea if you sleep with your mouth open? what are some reasons someone would sleep with there mouth open?

Maybe : But as you relax you jaw often opens and drops. You would have sleep apnea if you stopped breathing or gasped for air

Sleep apnea: has to do with stopping breathing while asleep. It can only be diagnosed in a sleep laboratory. Snoring alone or sleeping with ones mouth open isn't diagnostic criteria for Sleep Apnea. If concerned, a pulmonologist can help with the diagnosis.