You might think mental illness is no singing matter — but the crazy-brilliant minds behind “Next to Normal,” the Tony-winning Broadway musical that opened Sunday night in Los Angeles, are out to prove you wrong.

Tom Kitt and Brian Yorkey’s musical about a mentally unstable mother and her barely-coping family is as close to a masterpiece as American musical theater is likely to get. Earlier this year, “Next to Normal” snagged a Pulitzer Prize, the only musical to do so since “Rent” in 1996.

Beyond having the same director — the boundary-pushing Michael Greif, who loves his many-tiered stages — “Rent” and “Next to Normal” epitomize the modern-day “serious musical,” with their pop-rock scores and social consciences. “Spring Awakening” is another example.

But good as “Rent” and “Spring Awakening” are, “Next to Normal” is even better. The nearly 40-song score might not be as instantly memorable, but songs like “I Miss the Mountains,” “I Dreamed a Dance” and “You Don’t Know” stick with you in more profound ways, as feelings rather than as words or melodies. Each song packs a fresh emotional wallop, barely allowing time to recover before the next one starts. It’s a wonder that one woman is basically in charge of them all.

But Alice Ripley is no normal woman. As Diana, matriarch of the Goodman family, Ripley carries the show, summoning up a preternatural endurance that never gives out. She runs the gamut of complex human emotions — by turns manic, hopeless, apathetic, suicidal, hopeful — stopping short only of happiness. But in her words, “People who think they’re happy just haven’t thought about it enough.”

Undone by personal tragedy early in her marriage, Diana’s mind throws up its strongest defenses. Her doctors call it bipolar disorder. They prescribe every kind of pill, each as inefficacious as the next. When Dr. Madden recommends a more extreme course of treatment, her husband Dan (Asa Somers) is faced with a difficult decision.

Helping Diana get by is her son Gabe (Curt Hansen), who isn’t what he appears. Lost in the shuffle is the Goodmans’ daughter Natalie (Emma Hunton), a bright girl driven to self-loathing by her seemingly uncaring parents.

Hunton and Hansen are real finds for these parts. Hunton, especially in scenes opposite her geeky-adorable boyfriend Henry (a perfectly cast Preston Sadleir), shines, and her singing is pitch-perfect.

Hansen, so good last year as the grieving Frankie Epps in Center Theatre Group’s production of “Parade,” is even better in this meatier role. His “I’m Alive” — seductive and passionate — is on a par with the original, and the impossibly high last note might actually be an improvement.

Somers’ Dan is fine as well, if somewhat overpowered by the others. His final scenes, which occur in an otherwise weaker second act, are emotionally complex and well played.

But it’s Ripley who keeps everything together. Her pounding vibrato pulsates like some alien instrument throughout the Ahmanson (sounding better than ever, perhaps thanks to the onstage band). She acts with her entire body, but especially with her hands. They point and caress and drape and reach. Her eyes perpetually wide open, she embodies the image of a woman forced into thinking she’s ill, but secretly unsure. Her performance is as affecting as they come.

Mark Wendland’s stage looks like an urban jungle gym, and it’s brilliantly lit in rich shades of deep purples and glaring oranges by Kevin Adams. There was one point, in the evolution of this musical, that not everything meshed well together, but no more. Everything is in sync — except, of course, Diana’s mind.

The powerful subtlety of the ending is slightly vitiated by a rousing final song, but without it, we might never recover from this emotional ride. After the inevitable standing ovation, exhaustion sets in, but not a fatiguing exhaustion. It’s the kind that feels well-earned and triumphant — the exhaustion of being alive.  

Reach Senior Arts Editor Jason Kehe here.