The first is physiological, for example, drinking strong tea, coffee and other excitatory drinks before bed can cause insomnia. The second is physical reasons, disease or physical discomfort such as pain, cough, palpitations, itchy skin and other symptoms can cause insomnia. The third is the psychological reasons, emotional excitement, excitement, fear, anxiety and other bad state of mind can lead to insomnia. The fourth is drug causes, such as taking amphetamines, caffeine, ephedrine, aminophylline and other central excitatory drugs can cause insomnia.