CoSleep is a very versatile white noise sleep aid application that supports iPhone and Android, and can also detect sleep talk and smart alarm clocks. There are many types of white noise, but for modern young people, the class sounds of 24 courses (mathematics, English, philosophy, chemistry...) in a small sleep are probably the best sleep aid white noise. And even if you still can't sleep, you have learned knowledge by the way. Of course, the sleep aid of hundreds of idols is also very good.