Nine out of ten patients who come to our department start with this phrase: “Doctor, I can’t sleep well.” Many people will think: “Wow, that’s easy, just prescribe some sleeping pills and everything will be taken care of. You think too much. There are many reasons for insomnia, so many that we can lose sleep. Therefore, as doctors, we need to find the root cause of insomnia, and then we can treat it. First of all, “3 months” is the watershed to distinguish whether insomnia is short-term or long-term. Short-term insomnia is often related to life events, such as illness, job loss, love loss and arguments, and many people can come out of these events and return to normal. Long-term insomnia requires more attention and has a variety of causes. Nearly 45% of patients with chronic insomnia have a psychiatric disorder. The most common ones are depression and anxiety. The most characteristic symptom of insomnia in depressed patients is early awakening. Patients who are depressed are usually sullen and sad all day, uninterested in doing anything, and even have anhedonic thoughts. If you find yourself with suspected depressive symptoms, you can search for the Depression Self-Assessment Scale online and do a self-assessment. Some people may say, “I’m depressed because I can’t sleep, so I won’t be depressed if I sleep well.” At this point, it is worthwhile to experiment and take sleeping pills to get a good night’s sleep to see if your mood can be completely better after sleeping well. Insomnia in anxious patients usually manifests itself as difficulty falling asleep. Anxious patients usually have tension, worry and fear about many things, and in severe cases even muscle tension and fidgeting. If you suspect that you have anxiety symptoms, you can search for the Anxiety Self-Assessment Scale on the Internet to assess yourself. Other mental disorders that can cause insomnia include post-traumatic stress disorder and substance abuse (alcohol and caffeine abuse are the most common). In addition, about 10% of patients who have had insomnia for more than one month have a medical condition or substance use. In general, there are several types of physical illnesses associated with insomnia: lung disease, hypertension, diabetes, cancer, chronic pain, or heart failure. Nearly 25-30% of patients with Parkinson’s disease and Alzheimer’s disease are also plagued by insomnia. In addition, insomnia may also be caused by taking specific medications, such as central nervous system stimulants like caffeine, methylphenidate, amphetamines, and modafinil; and excitatory substances for the whistling system like theophylline; as well as glucocorticoids and antidepressants. About 5% of people with chronic insomnia are suffering from insomnia caused by some other sleep disorder. The most common of these is sleep apnea. This is manifested by loud snoring, backward breathing, grunting and interruption of whistling during sleep, and often brief awakenings when they resume whistling. In fact, sleep apnea is the cause of up to 90% of chronic refractory insomnia. Diagnosis of the etiology in this area can be achieved by perfecting polysomnography. Difficulty falling asleep is present in 85% of restless legs syndrome. It is characterized by discomfort in the legs when lying down and preparing for sleep, but this discomfort improves again after moving the legs. In addition, periodic leg movements during sleep and circadian rhythm sleep-wake disorders can cause insomnia. Only when these causes are excluded can we consider it to be simple insomnia. It is the right choice to use sleeping pills at this time. However, if you are a patient with insomnia of “other causes”, the first priority is to treat the original cause. Otherwise, taking sleeping pills is not the cure, or even harmful. For example, like sleep apnea patients if you take sleeping pills, it may instead aggravate the sleep apnea.