After I read he report I consciously gave attention to the music of Mozart and others like Bach and Beethoven. It's not easy to classify if only Mozart's music has repetitive melodies and others' don't, but still there's no doubt that in many of Mozart's compositions a particular melody flows around throughout the piece, very much like a theme music or like a hymn.
Here are some examples.
String Quartet No. 17 in B flat major ('Hunt'), K. 458
Andante-Grazioso - this one is perhaps a very good example of the repetitiveness in Mozart's music - it keeps on repeating like a hymn.
Symphony No. 25 (Titan theme music)
Symphony No. 40 (Salil Chowdhury's Itna Na Mujhse Tu Pyaar Badha)
The repetitiveness in music having a calming effect may not be a new thing. I can't say if there's any connection, but still it may not be just a coincidence also that all religious chants are very much repetitive almost in all cultures. The Mantras are always chanted in a typical repetitive fashion. There's no doubt that any hymn or chant is meant to soothe or calm our minds. Perhaps it's a very primitive intuition that was known to the mankind for ever and it came naturally more to Mozart than other composers.
I remember that my grandmother and other elder people at home used to say that it's good if pregnant mothers listen to religious songs or Gayatri Mantra or some other mantras because that is likely to have a very good impact on the baby in the womb. I heard a similar thing from Lata Mangeshkar. In an interview she mentioned that her father Dinanath Mangeshkar used to always sing good classical songs and read pieces from classical literature every time her mother had baby in her womb. She even claimed that the extraordinary sense of music in the Mangeshkar siblings might be due to all the music they all had heard since they were in wombs. A similar reference is found in the Mahabharata where Abhimanyu learns about a particular battle art while in womb. I haven't come across any scientific research on whether anything that babies hear while in wombs has any far lasting impact, but this particular research about repetitive music having calming effect on premature babies may be of some relevance. Also the age old Indian belief that listening to religious songs, which are in most cases repetitive in nature, in womb is good for the babies may have something to do with it.