There are more diseases that cause drowsiness, and drowsiness can occur due to cold, fever, diabetes, hypothyroidism, anemia, and insufficient blood supply to the brain. Infectious diseases such as colds can increase energy consumption when fever occurs, and the brain can induce drowsiness due to nutritional deficiencies. Diabetic patients can have changes such as weakness and drowsiness due to insulin deficiency or insulin utilization disorders, which can affect the brain’s use of glucose. Hypothyroidism can have impaired energy metabolism, and the brain can experience drowsiness due to lack of energy material support. In anemia, the blood’s ability to carry oxygen decreases, and the brain can experience increased sleepiness due to insufficient oxygen supply. Sclerosis and narrowing of cerebral blood vessels can reduce the blood supply to the brain, and energy substances such as oxygen and glucose cannot be delivered to brain cells in time, which can induce increased sleep.