Sleep deprivation means that a person is not allowed to have a normal rhythm of sleep. What would be the effect on the human body if one did not sleep for several days and nights? It is said that from ancient Rome until the Nazis in Germany used to kill prisoners by not allowing them to sleep, which is proof of the lethality of sleep deprivation. It is well known that sleep has the function of restoring energy and eliminating fatigue. In our daily life, the sleep-wake cycle is the most stable, it is both regular and rhythmic. In addition there can be memory loss, inattention and difficulty in thinking. If you do not sleep for 2-3 days, you may experience physical discomfort, such as tingling in the hands and feet, allergy to pain, burning sensation in the eyes, tingling, double vision, etc. Some sleepless people may experience mental abnormalities, delusions and hallucinations, seeing a rope and mistaking it for a snake, hearing simple sounds such as speech and children crying in their ears, and in severe cases, they may have disordered thinking and fragmented delusions such as delusions of victimization, and their speech often fails to make sense. Those who do not sleep for more than 100 hours may develop schizophrenia-like symptoms, which can lead to death in severe cases. Prolonged sleep deprivation can also cause a series of neurological and biochemical changes, mainly manifested as finger tremors, difficulty in pronunciation, poor motor coordination, muscle relaxation, and slow response to external stimuli. In terms of blood biochemistry, there are changes in the production of ATP and ADP, and the total plasma lipids, β-lipoprotein, and cholesterol are all elevated to varying degrees. Sleep deprivation can cause great damage to various functions of the body, but with a good night’s sleep, all problems will disappear.