Being able to sleep may be due to physiologic factors (lack of sleep, overwork, etc.) or pathologic factors (hypothyroidism, cardiovascular disease, liver disease, etc.). 1. Physiological factors (1) Lack of sleep: for example, often staying up late without enough sleep or noisy surroundings affecting the quality of sleep, so especially able to sleep. (2) Excessive exertion: Doing heavy physical work during the day and overworking, so you can sleep especially well. 2. Pathological factors (1) Hypothyroidism: due to the abnormal secretion of thyroid gland, it can be manifested as easy to be sleepy and especially sleepy. (2) Cardiovascular disease: because of insufficient cerebral blood supply, atherosclerosis and lead to sleepiness, sleepiness, dizziness, headache and other symptoms. (3) Liver diseases: viral hepatitis, alcoholic liver disease, cirrhosis, etc. can cause symptoms such as fatigue, sleepiness, and discomfort in the liver area. If self-regulation can not be relieved, it is recommended to consult a doctor in time to identify the cause of the disease and follow the doctor’s instructions for treatment.