VanWyngarden explains the song as the feeling when "a parasitic alien is in your head, controlling things".

[2] On March 30, 2012, the band premiered "Alien Days", at a show in Bogotá, Colombia,[3] at the Festival Estereo Picnic.

On March 11, 2013, MGMT confirmed on their Twitter account that a Record Store Day release would be a cassette tape (with download card) of the studio version of "Alien Days", which became available on April 20.

[4] On March 22, 2013, RSD confirmed that this single will be a Record Store Day exclusive limited release.

[5] On April 17, the band previewed the song in a stop motion video showing the unpacking of the cassette.