Guitarist Bill Kelliher originally came up with this song. Bassist Troy Sanders told Artist Direct: "From the get-to, it sounded like some grown man rock'n' roll [Laughs]. That's how it feels."

He added: "'Asleep in the Deep' is not a song that we could have or would have written on our very first record. It takes a level of maturity as a band, at least for the four of us, to create something that encapsulates that type of a mood. It's that surreal 'floating on clouds' element, yet we're dealing with really deep and intense personal issues. We're able to let that out. That's a wonderful outlet from the lyrical standpoint."

The song features additional background vocals by Valient Himself from Valient Thorr. Sanders said: "He popped into the studio to visit, and we were like, 'Hey, here's a vocal part for you!' He sang with us on the chorus."

Mastodon teamed up with Skinner, the Oakland-based artist who created their psychedelic Once More 'Round the Sun album art, for the song's music video. The clip shows the strange and epic night-time adventures of a house cat after his owner nods off to sleep.

Skinner said: "This concept was birthed out of my curiosity for what a cat really does at night while we are asleep. Where do they go? Cats have a very mysterious myth to them and I thought it would be cool to explore that, as little nocturnal heroes. I decided to put a sort of Joseph Campbell hero myth spin on it and add some Jodorowsky psychedelia as well. I'm more than excited about the way it came out! I love it."