Johann Sebastian Bach composed a set of 24 exercises (German, Uebungen) for his students. For me, these are some of the most amazing sounds creatively assembled by their composer.
In particular, the very first one of these, in Book 1, is so relaxing, possibly because the repetitions lead to a sense of hypnosis for me.
Here is the excellent Dutch Harpsichordist, Siebe Henstra, to play this music for you:
