What causes intense jaw stiffness immediately upon waking up?
1. Introduction and Direct Answer Experiencing significant jaw stiffness immediately upon waking is predominantly caused by nocturnal bruxism, a sleep-related movement disorder involving the continuous grinding and clenching of the teeth. This sustained muscular contraction depletes cellular oxygen and accumulates metabolic waste products, leaving the masticatory muscles profoundly fatigued and rigid by morning. In addition … Read more