Old sleepiness is not necessarily a precursor to serious illness, may be related to sleep deprivation, may also be due to insufficient cerebral blood supply, iron deficiency anemia and other reasons. 1. Lack of sleep: If you often stay up late to work overtime, or stay up late to play with your cell phone, etc., resulting in insufficient sleep, the brain does not get enough rest, which may cause old sleepiness, and may be accompanied by mental fatigue, lack of concentration and other manifestations. 2. Insufficient cerebral blood supply: common in patients with hyperlipidemia and cerebral atherosclerosis, due to high blood viscosity, narrowing of the lumen of blood vessels, and weak vascular elasticity, resulting in slow blood flow, resulting in insufficient blood supply and oxygen supply to the brain, which may cause sleepyness, and may be accompanied by dizziness, headache and other symptoms. 3. Iron deficiency anemia: due to insufficient blood volume, the number of red blood cells in the blood is significantly reduced, the ability of blood to carry oxygen is insufficient, resulting in the brain is in a chronic lack of oxygen, it may show the old sleepy, can be accompanied by weakness, pallor and other manifestations. It can be seen that old sleepiness is not necessarily a precursor to serious illness, if accompanied by obvious symptoms, should also be taken seriously, it is recommended to go to a regular hospital as soon as possible, through the improvement of the relevant examination, diagnosis of triggers, to give targeted treatment.