Children’s sleepiness and lack of appetite after fever is generally a normal phenomenon, but does not exclude the occurrence of neurological and other diseases, such as encephalitis, myocarditis, etc., should be promptly consulted to identify the cause of the disease. 1. Normal phenomenon: children’s sleepiness and lack of appetite after fever, usually due to the decline in body functions, resulting in physical fatigue, loss of appetite, may also be a fever caused by nerve involvement and dehydration has not yet fully recovered from the phenomenon. 2. Pathologic phenomena: (1) Encephalitis: caused by viruses, bacteria, autoimmune system disorders, etc. As the blood-brain barrier of children is still imperfect, microbial infections can enter the brain through the bloodstream, and the patients can have the symptoms of fever, lethargy, accompanied by nausea, vomiting, and in severe cases, epilepsy and hallucinations can also occur. (2) myocarditis: mainly due to viral infections, its symptoms vary in severity, patients may have no obvious symptoms, some patients may have fever, extreme fatigue, generalized tiredness, drowsiness, appetite decreased significantly, etc., the condition of the serious patients may also appear shortness of breath, dyspnea, chest pain and other manifestations. Children’s fever after drowsiness and lack of appetite, if the symptoms exist for a long time or progressive aggravation, the family should pay attention to, timely consultation, improve the relevant examination, by the doctor to carry out targeted treatment.