Symptoms such as diarrhea and vomiting may occur when eating overnight meals that have been kept at room temperature. If it is kept at a low temperature, it is edible and generally not harmful. If overnight meals are kept at room temperature, the number of bacteria in the meal will increase and many pathogenic bacteria will multiply in the meal. The toxins produced by the bacterial reproduction in the gastrointestinal tract may cause vomiting, diarrhea and other indigestion symptoms, and in severe cases may cause acute gastroenteritis, long-term consumption of overnight meals is a certain harm to the body. If it is placed in the refrigerator or low-temperature conditions for preservation, pathogenic bacteria can not reproduce quickly, so generally will not produce harm, but placed in the time can not be too long, too long will be spoiled. It is recommended that you try not to eat overnight meals, if you need to eat, at least should be placed in the refrigerator to save reasonably, and should not be placed for too long.