CoolCool is a mobile application designed based on cognitive behavioral therapy for insomnia, designed to inform everyone about sleep and help them overcome insomnia on their own.Cognitive behavioral therapy for insomnia is a non-pharmacological method that can help you develop good sleep habits and treat insomnia based on scientific knowledge about sleep known to date. The willingness and willingness to learn on your own is essential to improve your sleep through scientific methods, and we are confident that you have the capacity to improve your sleep.This application recommends scientific sleep time based on the sleep diary being written. It is designed to be used for 6 weeks, but you can use it for as long as you want even after 6 weeks. In addition, users can check whether their symptoms are actually improving by checking the changes in sleep time and sleep efficiency in a graph through a daily sleep diary. The contents presented in this application have been reviewed by Korean psychiatric specialists.This application has been developed for both stand-alone use and as an adjunct to professional care, but it is not a substitute for professional care and states that you must seek the advice of a doctor and not use the app before making a medical decision.