Ask HN: Long duration videos or podcasts to gently promote sleep

I’m eternally grateful to the History of the Universe YouTube channel [0] for improving my sleep. I don’t mean that in a negative way. I usually put these videos on headphones when I have trouble sleeping and reliable fall asleep. It’s just the right combination of long duration, cosmic subject matter and soothing voice over. Any similar recommendations in this vein?

[0] https://m.youtube.com/watch?v=3Illx0WkCxU