This is especially common in people who sleep with their mouth open, have allergies, or already struggle with sinus sensitivity.

2. You Experience Neck, Shoulder, or Muscle Stiffness

If you wake up with a stiff neck, sore shoulders, or tight muscles, the fan could be contributing. Continuous airflow—especially cool air—can cause muscles to tense slightly during sleep. Over several hours, this tension may lead to soreness or stiffness in the morning.