The possible clinical causes of nighttime nosebleeds in summer in 5-year-old babies include environmental factors such as dry air and disease factors such as nasal trauma and malnutrition. 1. Dry air: high air temperature in summer, low humidity in the air; or use of air conditioning without humidification, will also make the air humidity lower. The above situation will easily make the nasal mucosa dry and broken, and thus easy to nosebleed. 2. Nasal trauma: When the nose is hit by external forces or frequently picking the nostrils with the hand, it may cause the nasal mucosa to be damaged and the symptoms of nosebleeds. 3. Nutritional deficiencies: If the child is a picky eater or lacks nutrients, it may cause insufficient intake of vitamin C, which makes the gums and nasal passages prone to bleeding. If it is an environmental factor, you need to make appropriate adjustments; if it is a disease factor, it is recommended to go to the hospital as soon as possible for examination and targeted treatment.