Every story in the Lullable app is written before it is read aloud, and the written version is on this site in full. That is unusual enough to say plainly: most sleep audio exists only as audio, so if you would rather read yourself to sleep than put something in your ears, the catalogue is mostly closed to you.
These are not fiction. A Roman bathhouse at the hour the fires go out, the museum of things that have drifted to the floor of the sea, the eleven-year argument about the width of a wooden pallet. The material is true, and it is chosen for being genuinely interesting and entirely inconsequential — nothing here resolves, nothing is at stake, and nobody is waiting for you to find out what happens.
Each one gives its ending away in the first minute. That is the whole mechanism: a story you already know the end of is a story you are permitted to stop reading. Reading in bed usually fails because the book is trying to keep you there. These are trying to lose you.
If you would rather be read to, the same stories are narrated in the app — in a male voice or a female one.