[PO-HOP] On the first verse of "Rap Rehab," a playfully introspective track on Oregon Failure, the newest album from Portland MC Sleep, the 37-year-old poses a question that most rappers undoubtedly ask themselves when closing in on middle age: "What do I do now?" It's a dilemma rooted in the fact that hip-hop—maybe more than any other music genre—is constantly reinventing itself. Often, the only way for MCs to stay relevant is to reinvent themselves along with it.

In Sleep's case, though, the question is more satirical than literal: Over his decade-plus career as a member of respected Northwest rap outfits Oldominion and the Chicharones, his sound—rapid-fire lyricism over drum-slapping beats—has remained pretty much the same. His refusal to bend to the rap trend du jour, aside from a brief, ironic foray into Auto-Tune, is certainly a result of coming up in the early 2000s, when there was a clear divide between the sugary mainstream and the lyric-driven "underground." Oregon Failure sounds like it was plucked straight from a CD rack in that era, to both its benefit and detriment.

The album succeeds when Sleep utilizes his lyrical dexterity to tap his inner Beastie Boy and have fun. On "You Ain't Shhh," he yells out comic-villain threats ("I'm going to crush you!") while spitting inane reassurances about his talents on the mic.  On "Rap Rehab," he jokes about hosting a "support group for washed-up rappers" and finding new employment now that he's realized that he'll never be famous. "The only thing I ever been good at was cussing," he says.

Elsewhere, things get more serious, and while Sleep's machine-gun delivery is always impressive, it can become tiresome in the moments meant to strike an emotional chord. You can't help but wish he'd occasionally slow things down and focus on delivering the message at hand. But it's tough to teach a 37-year-old rapper new tricks.

SEE IT: Sleep plays Ash Street Saloon, 225 SW Ash St., with Bad Habitat, Kinetic Emcees, Das Leune and Ether XOXO, on Sunday, April 20. 9 pm. $8. 21+.