When Wolverine awakes in his 1973 self in X-Men: Days of Future Past he hears a song on the radio. This same song is heard when he awakes in his future self again at the end of the movie, which is likely to evoke feelings of Déjà vu in him (and the audience) and to let him doubt reality for a moment.
What song is this and is there any further significance to this particular song?