The music bass guitarist Greg Greenberg ’05 makes with the Austin, Texas, band Seven Circles can get pretty heavy, but none of it is as heavy as Greenberg’s main gig as an ICU bedside nurse. “It’s the most complicated patients, the sick­est people in the hospital,” he says. “The music is therapy, it’s release. It’s a way to keep myself sharp, but in a manner that has nothing to do with dire clinical situations.”

Greenberg started playing with Seven Circles in 2014, just as he was moving to a new home in Austin and starting a new job in a local ICU. A coworker pointed him in the direction of Seven Circles’ leader and guitarist Robert Howard, who needed to fill the band’s bass slot. “It was perfect timing,” Greenberg says, and “the music was so strik­ing.”

The music Greenberg makes with Seven Circles is compelling both in its simplicity and the way it builds to an almost-overwhelming com­plexity. The trio’s music fits primarily into a genre that’s been dubbed “post-rock” (think Sigur Rós, Explosions in the Sky, or Mogwai), and the nine tracks that make up its most recent release, Retrograde Pa­rade, move through shifting time signatures and dynamic expansions and contractions with a loose energy that can make it easy to miss how carefully controlled the playing is.

Along with Greenberg’s bass, Seven Circles features guitar and drums, but no vocals. The lack of a singer and lyrics allows the trio to play as big and loud as it wants. “No vocals means we can push the volume up, because we’re not going to drown anyone out,” says Greenberg.

Most Seven Circles songs begin with Howard playing his guitar through a series of sampling/looping pedals, manipulating and stack­ing his parts into what Greenberg calls “tidal waves of noise.” From there, Greenberg and drummer Russell Hudson build on Howard’s rock-heavy foundation and keep the psychedelic instrumentals mov­ing forward and skyward.

The band’s live performances, mostly at small Austin clubs, also feature a choreographed light show. “We have LED lights in all of the drum shells and speaker cabinets, and all of the time-signature changes and tempo changes are reflected in the lights,” says Green­berg. “Even if an audience member isn’t a music nerd, they can watch the lights for a visual hook.”

Seven Circles is currently keeping a light schedule while Greenberg finishes a master’s degree to become a nurse practitioner, but he’s not exactly taking a musical hiatus. Greenberg also plays with Instar, a recording-only project that features spoken-word vocals. His work with Instar can fit around his hospital shifts and school schedule, as it involves musicians contributing parts from far-flung locales and there is no onstage component. (Instar’s most recent release, The Ex Nihilo Cycle, is based on a science-fiction story suite by Tel Aviv-based writer Eden Kupermintz.)

Greenberg’s music has brought him under the umbrella of the Southwest Post-Rock Collective, a supportive network of bands that make instrumental music, and both Seven Circles and Instar take ad­vantage of the Bandcamp platform for digital distribution. Greenberg is content for now with playing local shows and not printing up CDs or LPs. “This is not a business,” he says. “It’s not a way for me to secure my prosperity. This is something I do because I love to do it.”