There are many causes of insomnia, which experts have categorized into five major groups: physical, physiological, psychological, mental illness, and medications. Insomnia caused by physical diseases Physical diseases that cause insomnia include heart disease, kidney disease, asthma, ulcer disease, arthritis, bone and joint disease, gastrointestinal disease, hypertension, sleep apnea syndrome, hyperthyroidism, nocturnal myoclonus syndrome, brain disease, etc. Jin Lichun, Department of Neurology, Third Affiliated Hospital of Henan University of Traditional Chinese Medicine Insomnia caused by physiology Changes in the environment can cause physiological reactions, such as changes in the sleep environment when riding in cars, boats and airplanes; strong light, noise, too cold or too hot in the bedroom can cause insomnia. Some people are highly adaptable to the environment, while others are very sensitive and poorly adapted, and can’t sleep well when the environment changes. Insomnia caused by psychological and mental factors Psychological factors such as anxiety, restlessness or depression, unhappy mood, etc. are important causes of insomnia. The blow of life, the pressure of work and study, the attempted will and the change of social environment can cause psychological and physiological reactions, which lead to abnormal function of the nervous system and cause dysfunction of the brain, thus causing insomnia. Insomnia caused by taking drugs and other substances Taking central excitatory drugs can lead to insomnia, such as the diet pill amphetamines. Long-term use of sleeping pills, once withdrawn, can also lead to withdrawal symptoms – shallow sleep and more nightmares. Tea, coffee and cola-type drinks contain caffeine, a central nervous stimulant, which can cause insomnia when consumed in the evening. Alcohol interferes with a person’s sleep structure and makes sleep shallow, and once you quit drinking it can also cause insomnia due to withdrawal reactions. Insomnia caused by the fear of insomnia Some people have high expectations of sleep, believing that if they sleep well, their body will not be invaded by all kinds of diseases, and if they sleep badly, they will be prone to various physical problems. This excessive superstition about sleep increases the pressure of sleep and can easily cause insomnia. People inevitably have bad sleep, but some people are too worried about this temporary bad sleep and its impact on the body, the thought of sleep, will be conditioned to fear, always thinking about the need to sleep well, but make it more difficult to fall asleep. This will form a vicious circle of fear of insomnia – committed to sleep – insomnia – more fear of insomnia. In the long run, it is likely to evolve into chronic insomnia.