How to tell why i clench my teeth while i'm sleeping?

Bruxism: If you grind or clench your teeth chronically, you may notice erosion on the surfaces of your teeth. In addition you may pain, discomfort, or stiffness in moving your jaw. It is recommended you consult a sleep medicine specialist as bruxism may point to an underlying medical issue, such as sleep apnea, especially if you snore, have excessive daytime sleepiness as well as other symptoms.

Evalutaion: Bruxism may also be caused be stress.

Clenching: Clenching can be increased by stress in your life. It also can occur because of sleep apnea. If you are tired all the time, or snore you should be evaluated for sleep apnea. Some dentists can treat sleep apnea with an oral appliance instead of cpap.