Morbidity refers to illness or disease, while mortality refers to death. Morbidity can refer to both physical and mental conditions, and often involves chronic diseases that worsen over time and reduce quality of life. Co-morbidity means having more than one illness simultaneously. Common student health problems include the common cold, food poisoning, influenza, sprains, and bleeding noses. Poor student health is linked to worse school outcomes like failure, retention, and dropout. Maintaining nutrition, weight, and fitness can help improve student health.