Insomnia is classified according to the etiology: 1. Primary insomnia: refers to insomnia without obvious causes, such as physiological state, occasional insomnia before and after menstruation; 2. Secondary insomnia: that is, insomnia caused by obvious causes such as somatic diseases, pain, psychological disorders, living environment and drug or substance dependence. Insomnia can be classified according to time: acute insomnia, insomnia for <1 month; subacute insomnia, insomnia for >1 month, <6 months; chronic insomnia: insomnia for >6 months.