If you are sleepy and tired after the vaccination, you should first consider the adverse effects of the vaccine. Most of the vaccines are inactivated vaccines, and like other inactivated vaccines, some people may experience systemic adverse reactions after receiving the vaccine. In addition to being sleepy and tired, they may also experience headache, fever, loss of appetite, diarrhea, vomiting, etc. Local symptoms, such as redness, hard lumps, itching, soreness, etc., may also occur at the site of vaccination. Generally, the symptoms are mild and do not require special treatment, and you can recover in a short time by ensuring rest. However, if these symptoms persist and are accompanied by other serious discomfort, you can go to the hospital to clarify the cause. Secondly, if you are sleepy and tired after the vaccination, it may be due to the lack of oxygen to the brain caused by excessive tension during the vaccination, which may lead to muscle weakness and sleepiness. In addition, we cannot rule out the possibility that the lack of sleep due to mental stress before the vaccination may also lead to sleepiness and lack of energy the next day, but the sleepiness and tiredness after the vaccination is not related to the vaccination.