The melatonin drug has a certain role in promoting sleep, but it is exogenous melatonin, and the body secretion of melatonin there are certain differences, need to follow medical advice to take medication, strictly prohibited to increase or decrease the amount of medication. The melatonin will have a series of adverse effects on the body, including psychoneurological symptoms, increased liver, gastrointestinal burden, causing endocrine disorders, etc. 1, psychoneurological symptoms: exogenous melatonin will affect their own melatonin secretion, taking too much may lead to daytime drowsiness, night wakefulness, or poor mental state during the day, inattention, slow reaction, sensitivity, etc.. Long-term overdose of melatonin, can aggravate the symptoms of insomnia, thus becoming dependent on melatonin, as well as anxiety, depression and other psychiatric symptoms; 2, aggravate the liver, gastrointestinal burden: melatonin is a hormonal substance, need to be metabolized by the liver, too much melatonin, may aggravate the burden on the liver, and a large intake will have an effect on the gastrointestinal mucosa, may cause gastrointestinal discomfort symptoms; 3, endocrine disorders. Long-term large amounts of melatonin, can affect the body’s endocrine function, resulting in thermoregulation and sex hormone regulation disorders, resulting in lower body temperature, female infertility, male libido reduction and other performance; 4, other: melatonin to eat more can also have adverse effects on the cardiovascular system and immune system function, any drug should not be taken in excess. Melatonin is mainly used to assist in the treatment of insomnia caused by the lack of melatonin, for other causes of insomnia no significant effect, insomnia patients are recommended to actively seek medical treatment to find the cause of treatment, and follow medical advice on the use of drugs.