Uh, I do similar thing. I use narrated let's plays or podcasts on YouTube to go to sleep in the evening and YouTube knows this. It knows my habits so much that even not to recommend stuff I listen every evening, durning daytime. Only when I open my phone in the evening reccomendations are suddenly full of stuff I want to listen to get to sleep.

I use YouTube bc it autostops playing and turns phone off when I'm already sleeping. And funnily enough, ads help me start sleeping faster :D