When you hit zero sanity, it's time to take a break or refill with some OP or sanity potions. But what if it drops below zero? Your instant noodle diet might be causing some serious issues like headaches, coughing up blood or vomiting. Dr. Kal'tsit will be watching over you closely, but she doesn't seem too happy about it All rights belongs to the original creator of Arknights, Hypergryph Network Technology Co. Ltd