I generally drink chamomile tea because I like it. However… when I was in Germany once I had some sort of ear, nose or throat issue (I don’t remember which now, maybe all of the above) and the doctor told me to stew some chamomile tea and breathe it in. It seemed to work, but I don’t know if it was just the steam doing the trick, though.
Also, I remember reading a story as a young child about Peter Rabbit. He got in some sort of bunny vs. farmer trouble, I recall, and at the end of his terrible, horrible, no good, very bad day, his mom made him some chamomile tea. Ever since then, I associate it with comfort. Add to that the fact that the Celestial Seasonings “Sleepytime” tea has chamomile in it, well you’ve got a lovely brew of the power of suggestion to lull me into a calm, drowsy state. I love drinking it at nighttime for that reason.