Often like to sleep, there are usually the following four main reasons: First, the most common reasons are excessive blood viscosity or high blood lipids, usually hypertriglyceridemia, hypercholesterolemia, excessive LDL in the blood, or increased high cut-off values in blood rheology as the main reason. Second, often like to sleep, sleepy and brain lack of oxygen related, usually with brain cell hypoxia, oxygen partial pressure is insufficient, carbon dioxide partial pressure is too high, blood oxygen saturation is weakened. Third, related to the cerebral arteries cerebrovascular blood supply is insufficient, vertebrobasilar artery ischemia is the main cause. Fourth, such as heart disease, coronary artery atherosclerotic heart disease caused by cardiovascular blood supply is reduced, the body lack of oxygen will also cause drowsiness.