There are many reasons why patients suddenly become sleepy, the most common reason is that the patient’s body is in a state of fatigue, or after excessive use of the brain, brain fatigue will also feel the symptoms of sudden sleepiness, the patient will be able to recover after a nap, and the mental and physical strength are quickly recovered. There is also the patient suddenly sleepy, may also be the brain tissue local ischemia, lack of oxygen, may be with the air environment is not good or blood circulation is not good. It is suggested that if the patient frequently experiences this situation, he can consult the hospital to check the blood lipids, blood rheology, and transcranial Doppler, to observe whether the patient’s cerebral blood supply is problematic. If the viscosity of blood is relatively large and the patient is often prone to drowsiness, it is recommended to give the patient lipid-lowering and anti-viscosity treatments, and to eat less greasy food and more green vegetables and fruits in the diet.