People who experience both insomnia and anxiety exhibit a specific type of exhaustion that they understand very well. The exhaustion you feel extends beyond standard tiredness into a deep-rooted state of fatigue. Your brain will not help you sleep even though you feel tired. You lie in bed running mental calculations: if I fall asleep right now, I'll get five hours. If I fall asleep in thirty minutes, four and a half. The calculation itself prevents sleep, which feeds anxiety about not sleeping, which prevents…