Chronic sleepiness is not usually an early sign of cancer, and most cancers have no obvious symptoms in the early stages. Poor sleep quality or sleep apnea syndrome may present as chronic sleepiness. Diseases related to the internal medicine system, such as hypothyroidism and anemia, diseases related to the nervous system, such as Parkinson’s disease and dementia, and diseases related to the mind, such as lethargy and depression, may also lead to this condition. When sleepiness occurs, even with symptoms such as memory loss and slow reaction time, problems such as arteriosclerosis need to be ruled out through examinations such as cranial CT, MRI and cerebrovascular ultrasound. If patients are worried about cancerous changes in their bodies, they can go to the hospital for physical examination, which can help detect early cancerous changes that have not yet shown symptoms, and achieve early detection, early diagnosis and early treatment, as well as maintain a regular routine and a healthy diet, which can help prevent cancer.