Sometime Last Night debuted at number six on the US Billboard 200, with 31,000 copies sold during its first week, making it the band’s first top ten album.

R5 released their debut studio album Louder in September 2013, featuring the singles "Loud", "Pass Me By", "(I Can't) Forget About You" and "One Last Dance".

[2] The album was set to be released in spring 2015;[3] however, Rocky Lynch announced that it was pushed back because they wanted to "get it right" for the fans.

However, due to further production and revisions, Ross Lynch announced in a radio interview that the band has decided these songs will not appear on the album, because they wanted a "blank slate".

[12] "Wild Hearts" fuses "brilliantly shifting tempos," with "massive beats, and irresistibly sweet harmonies into an all-out powerhouse of an anthem.

[13] "Repeating Days", a "slowed down" track,[14] blends sad lyrics with melancholy guitar tones, gently pulsing beats[11] and raw vocals.

", "reflect the lyrical tendencies of the group that are focused on the good and bad of relationships as well as their classic rock and pop infused sound".

[citation needed] To correspond with the release of the album, audio versions of all standard edition songs were uploaded to the band's vevo account on YouTube.

Jamey Beth from Breakaway Daily said "Sometime Last Night [is] a selection of arena-sized pop songs shot through with gorgeously crafted melodies, electrifying harmonies, and lyrics culled from real-life stories the band’s been through over the past few years.

She wrote: "Overall, the album is produced in a way that accurately states how the band has developed and [...] [they] offer an easy-listening experience that has your head bopping along to each track, and singing along contently.

"[14] Comparing it to 2013's Louder, Tim Senda from Allmusic said that "Sometime Last Night doesn't get bogged down in soggy ballads, but instead deals in chipper, big-chorused midtempo pop."

[12] Sometime Last Night debuted at number 6 on the Billboard 200 chart dated August 1, selling 31,000 units in the week ending July 16.