The Chicago radio station WLIT starts their 24 hour a day Christmas music today because people and the ratings like it:

WLIT-FM 93.9 will play only Christmas music round-the-clock beginning at 4 p.m. Tuesday.
It is the earliest date in the station’s 22 years of hosting the format that it is making the switch.
Why? Listeners love it…
“The reason stations switch in early November is so they can get a ratings boost for the final few weeks of the survey,” he wrote in an email.
Which comes first: the audience demand for the Christmas music or the supply of Christmas music? Would anyone play Christmas music this early if there was not such a direct payoff?
Such a question could be asked in all sorts of domains, ranging from other Christmas material – do stores put Christmas decorations and displays up right after Halloween to drive demand or is that demand already there? – to products of the culture industries. If such a question could be answered more predictably, there might be more hits – records, films, TV shows, etc. – and fewer flops.
In the meantime, Chicago radio listeners will later today have the option to hear Christmas music all the time. Even in an age of music streamable on demand plus all sorts of other music formats, at least a few will turn to WLIT because predictable Christmas music is available.