Read the following research article: Bedtime Music, Involuntary Musical Imagery, and Sleep - Michael K. Scullin, Chenlu Gao, Paul Fillmore, 2021 (sagepub.com)

What is one hypothesis from this article? (Is it indeed a hypothesis? Or is it something else?)

This is the answer I have so far:

Usually, the hypothesis appears at the final paragraph of the introduction. This article hypothesizes the concept that some genres of music can interfere with sleep patterns by triggering persistent earworms that are sustained by involuntary memory reactivation mechanisms.

I just need to know if it is indeed a hypothesis or not. If so, how? If not, why is it not?