Chemotherapy is one of the most commonly used treatments for cancer. But while killing cancer cells, chemotherapy can also damage normal cells, and then cause a series of toxic side effects and adverse reactions such as sleep disorders, fatigue and anxiety. 1 Insomnia is one of the most common sleep disorders,2 and sleep deprivation is associated with increased risk factors for cancer and increases its incidence and mortality.3,4 Long-term chronic insomnia will aggravate patients' negative emotions, lead to fatigue-sleep disorders-depressive syndrome (F-S-D),5,6 reduce patients' immunity and disease resistance,7 increase the risk of cancer recurrence and metastasis,8 and form a vicious cycle, thus reducing the quality of life and treatment compliance of chemotherapy patients.9 The incidence of chemotherapy-related insomnia ranged from 54.72 % to 79.6 % according to tumor type.10,11

The main drugs used in modern medicine to treat insomnia are sedative and hypnotic drugs, but long-term use often leads to addiction, drug resistance and damage of liver and kidney function.12, 13, 14 Complementary and alternative medicine (CAM) has been widely used in the treatment of cancer and related diseases.12,15 A clinical practice guidelines published by the Society for Integrative Oncology(SIO) and the American Society of Clinical Oncology(ASCO) recommend the use of acupressure to treat chemotherapy-induced side effects, such as sleep disturbances, anxiety and depression.16 According to the Society for Oncology Nursing International Guidelines, auricular acupressure is recommended as an appropriate and promising technique for the treatment of chemotherapy side effects.17 Auricular acupressure is a type of CAM which is more acceptable to patients because of its noninvasive, convenient, painless and safety.18,19 Compared to other CAM, such as acupuncture, auricular acupressure is more friendly to cancer patients because it is non-penetrating and painless.A large-scale global scientific research result, which explored the study of acupuncture in the treatment of insomnia in 1999∼2018, found that systematic reviews and clinical trials focused most on electroacupuncture and acupressure in acupuncture treatment.20 Studies have shown that auricular acupoint compression treatment of insomnia effect is significant, the common choice of auricular acupoint is Shenmen, Xin, Pizhixia and so on.21,22 Auricular acupoint compression can improve the insomnia symptoms of chemotherapy patients, improve the quality of life, reduce the dosage of sedative drugs and adverse reactions.Previous systematic reviews have summarized the efficacy and safety of auricular acupressure for cancer-induced insomnia,23,24 found that patients with chemotherapy, one of the most common causes of cancer-related insomnia, had more severe insomnia than those receiving other treatments, such as surgery, radiation or hormone therapy.25, 26, 27 This study was designed to systematically evaluate the efficacy of auricular acupressure for relieving chemotherapy-related insomnia.