The incidence of insomnia is high, and the majority of us have experienced insomnia, however, most people’s insomnia is often caused by certain events, and after the events pass well, the insomnia situation disappears, such as facing high school exams, facing an important interview, etc. We often have trouble sleeping. Such a situation cannot be called insomnia, which means that this condition is not a disease. So, what kind of condition has met the diagnostic criteria for insomnia? I will share below the diagnostic criteria of the American Psychiatric Association for non-organic insomnia. Insomnia is a condition in which the quality and/or quantity of sleep is unsatisfactory for a considerable period of time. In diagnosing insomnia, the length of sleep generally considered normal cannot be used as a criterion for determining the degree of deviation, because some individuals (so-called short sleepers) require only a short period of sleep and do not consider themselves to be insomniacs. Conversely, some people suffer for their poor sleep quality, but their sleep duration is subjectively and/or objectively considered to be in the normal range. Among insomniacs, difficulty falling asleep is the most common complaint, followed by difficulty maintaining sleep and early awakening. However, the above conditions usually coexist in the patient’s complaints. Typically, insomnia occurs at times of increased stress in life and is seen in women, older adults, and people with psychological dysfunction and poor socioeconomic status. If a person has recurrent insomnia, he becomes increasingly fearful of insomnia and overly concerned about its consequences. This creates a vicious cycle that perpetuates the person’s problem. At bedtime, people with insomnia describe themselves as feeling nervous, anxious, worried or depressed, and their thoughts are racing. They often think too much about how to get enough sleep, personal problems, health conditions, and even death. They often try to deal with their nervousness by using eye medication or drinking alcohol. Early in the morning, they often complain of feeling drained; the daytime is characterized by depression, worry, nervousness, irritability, and an overwhelming preoccupation with themselves. We also often say that a child has sleep difficulties (not sleep per se) when there is difficulty putting the child to bed in life; difficulty in caring for the child to fall asleep should not be coded here, but it is classified in ICD-10 Chapter 21 (Z62.0, inadequate parental care). To confirm the diagnosis, the following clinical features are necessary: (a) complaints of either difficulty falling asleep, difficulty maintaining sleep, or poor sleep quality; (b) such sleep disturbances occur at least three times a week and last for more than one month; (c) preoccupation with insomnia day and night and excessive concern about the consequences of insomnia; (d) unsatisfactory quantity and/or quality of sleep causing significant distress or interfering with social and occupational functioning. Whenever quantitative and/or qualitative dissatisfaction with sleep is the patient’s only complaint, it should be coded here. The presence of other psychiatric symptoms such as depression, anxiety, or obsessions does not negate the diagnosis of insomnia if it is the underlying symptom or if the chronicity and severity of insomnia is such that the patient sees it as the underlying symptom, even if other psychiatric symptoms such as depression, anxiety, or obsessions are present. Other coexisting disorders should also be coded when symptoms are significant and persistent and appropriate treatment is necessary. It should be noted that most insomniacs are usually overly concerned with their sleep disorder and deny the presence of an emotional problem. Therefore, a careful clinical evaluation must be performed before the psychological basis for the complaint of insomnia can be ruled out.