With all of its hippie accouterments, “Hair” might seem like more of a novelty act than vital theater these days, but the groundbreaking 1960s rock musical is still a bracing experience for reasons that have nothing to do with its once-controversial full-frontal nude scene.

ArtsWest’s production is infectiously fun when the material calls for it, but it really excels in its disturbing and defiant depictions of a group of young people fighting against a world gone mad. “Hair” isn’t a series of flower-power platitudes; it’s a frayed-nerve exorcism of Vietnam-era anxiety.

Director David Gassner’s staging is eager and chaotic, valuing frenetic movement over order — an apt choice, given the show’s almost stream-of-consciousness plotting.

Nominally, the show charts the transformation of Claude (Mark Tyler Miller) from strait-laced guy to psychedelic wonder child to conflicted Vietnam draftee, but in a communal show like this, it’s the ensemble that matters.

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Whether in the jocular “Manchester England,” the caustic “Three-Five-Zero-Zero” or the hummable “Let the Sunshine In,” the ensemble is vocally commanding in attacking the Galt MacDermot-Gerome Ragni-James Rado score, under the sharp musical direction of Matthew Wright and Zachary Orts. Stacie Pinkney Calkins sets that tone early with her soaring solo in the opening song, “Aquarius.”

Though he’s outfitted with a ridiculous wig, Jeff Orton gives the show its impish playfulness as free-spirit Berger, while Sara Porkalob’s Sheila exemplifies the meaningful love binding these characters in her deeply felt turn.

Even if “Hair” had aged into a self-parodying hippie trip over the past four decades, this winning cast would likely have made it relevant by the sheer force of its contagious enthusiasm.

Dusty Somers: dustysomers@gmail.com