Whether hairy crabs can be eaten overnight depends on whether they are spoiled and whether they are well preserved. If the hairy crabs are refrigerated, well preserved and not spoiled, they can be eaten after heating; if they are not live hairy crabs and have not been refrigerated, it is not recommended to eat them after overnight. Cooked hairy crabs kept at room temperature are not recommended to be consumed after overnight. Hairy crabs belong to high-protein food, which is prone to breeding more bacteria and deterioration at room temperature. If live hairy crabs are refrigerated directly, they can be consumed after cooking. If the hairy crabs are cooked and refrigerated for not more than 6 hours, they are edible. If it has been refrigerated for more than 6 hours, it is generally not recommended to consume it. Spoilage may also exist if it has been refrigerated for too long. It is recommended to buy live, fresh hairy crabs and cook them as soon as possible after purchase for the best flavor and nutrition. If discomfort occurs, it is recommended to seek medical advice.