The causes of daytime sleepiness and lack of energy may be multifaceted, as follows: First, psycho-psychological factors: for example, some depressed patients are always lethargic, sleepy and poor in spirit during the day, and may need to visit the psychology department. Second, somatic factors: for example, insufficient blood supply to the cerebral arteries, which is mostly seen in middle-aged and elderly people who have long-term hypertension, diabetes and hyperlipidemia. Due to the lack of blood supply to the brain, ischemia and hypoxia, elderly people can also experience drowsiness during the day and always doze off and have no energy. Third, the blood system: for example, anemia, due to the low hematocrit in the blood, resulting in a reduced ability to carry oxygen, patients can also appear to have no energy and want to sleep.