Does `reactivePoll` prevents an app from being put to sleep?

That is, does the check function continues to be executed periodically, once all end user sessions disconnect?

I guess the answer is no. On the help for reactivePoll I read:

The user session to associate this file reader with, or NULL if none. If non-null, the reader will automatically stop when the session ends.

So, I run reactivePoll like this.
reactivePoll(2000, session=NULL, isThereNewFile, loadData)

However, when all end user sessions disconnect, reactivePoll stops working. (The loadData function sends to me a mail, so I know it doesn't work because I don't get any mails). Is there a way to have the app running, when no session is present? what is the meaning of session=NULL?