Clenching teeth during sleep
(night-time bruxism) is usually a habit in response to stress.
Less often it may also be due to a problem with your bite.
Many people who brux at night also do so during the day.
Check with your dentist for information on how to treat and possibly eliminate this habit. If you are having symptoms (pain, headaches, TMJ pain), you should be fitted for a nightguard or nti.