It’s the kind of idea that blooms late in a brainstorm session and then just never goes away until it becomes reality.

”How about a musical dealing with sleep disorders and featuring Sleeping Beauty?”

Or maybe the heartbreak of psoriasis merged with the Phantom of the Opera? No, probably intellectual property issues there. Stick with the one nobody else has thought of. Or acted on, anyway.

By some combination of imagination, urgency and goofiness, Sleeping Beauty Wakes has been roused at the La Jolla Playhouse. I didn’t nod off once.

A quartet of desperate patients are introduced as they fill out their medical histories. How desperate? They pounce on their doctor demanding action in a song – “Can You Cure Me?” – which might become a Medicare anthem.

Alas. the doctor explains, this is but an under-funded program in a second-rate hospital. But she’ll do her best on the morrow if everybody will cooperate by donning their test equipment, hitting the ward’s beds and working at dozing off.

Just before lights out, though, an unexpected patient arrives. Unlike everybody else in drab scrubs, she’s wearing a scarlet party dressed and she’s unconscious in the arms of an exhausted older man who identifies himself as the father. How long has she been this way? Over 700 years, he says, brushing aside questions about insurance by flashing a large wad of cash.

So meet Rose, the only child of a powerful king who, bewitched by an evil fairy, is wrapped in a deep sleep pending her True Love’s kiss. Her father traded “all the magic left in his kingdom” for the power to remain with her until she awakes.

This saga is related in an extended dream sequence involving all the patients and, when they awake the next day, they hail their doctor as a miracle-worker for bestowing the first good night’s sleep any of them have enjoyed in many a weary month.

But Rose sleeps on, since her curse makes her consciousness undetected by the rest of the world, as she explains during the dream sequence. Several princes brought in to kiss her, her father adds, succeeded in waking the rest of his kingdom. The border between fantasy and reality is little discussed.

OK, there are shows out there making good money with a lot less promising book than this. Fables are always fun. Modern intrusions are proven laugh-getters. And a good old boy-gets-girl subplot always works. So what if Rachel Sheinkin’s libretto plays loose with the rules of fantasy? It is a fantasy, after all.

Brendan Milburn has supplied the essential assortment of lively, bracing songs and the lyrics, by Valerie Vigoda, are adroit in an industrial sort of way: “The aristocracy’s hypocrisies are making me ill.”

In fact, there is a vitality to the piece that propels it past problems and into a finale that, while vague as to details, does seem to be upbeat, optimistic and restorative. For the boy and girl, anyway. The patients’ sleep problems apparently persist.

The aforementioned boy is a clever conceit. He’s a big gangling lug who serves as a sort of trustee in the ward, helping the doctor to pay for his own narcolepsy treatments. (Real medical folk, like fantasy purists, don’t want to look too closely at the details here.) In his condition, he tends to faint when confronted with emotion. So there are definite issues to iron out if he’s to be the one who awakes Rose. Let’s just say, in the long haul, they are good for each other.

Director Rebecca Taichman is attuned to the vitality of her creative colleagues and her staging is spare, nimble and flexible, just the sort of frame useful for a fantasy. Her handling of the leading men is deft; Bob Stillman make the father/king a plausible, even moving figure, the most polished characterization in the show, and Bryce Ryness probes the odd corners of his role while still reserving the room to be stalwart and romantic at the end.

The leading ladies are another matter. Aspen Vincent has the pipes for the part but her Rose lacks both the straight-on ingénue dazzle of a fairy-tale princess and the pulsating humanity of the real victim suggested in the writing. Instead, she seems to be most annoyed and frustrated that things don’t go her way.

And Kecia Lewis-Evans, who exhibits some startlingly subtle resources in suggesting the various complications of the doctor (not to mention the wicked fairy of the fable), is allowed to fling about so many flashy extremes of vocal and physical lumber that one becomes wary of her presence. At least there’s no hard-sell gospel number of the sort almost inevitable when a black character actress has a major role.

The other half of the company, the four patients, are notable for their variety and utility but the script allows them little more than perfunctory identification: The one who snores (Steve Judkins), the one who twitches (Adinah Alexander), the one who’s scared (Carrie Manolakos) and the one who acts swish (Jimmy Ray Bennett).

Riccardo Hernandez’ scenery is in the stripped-down and sterile La Jolla Playhouse tradition, appropriate here, and Miranda Hoffman’s costumes are notable mainly for the two layers of Rose’s scarlet. Lighting by Christopher relies a lot on pools and Leon Rothenberg’s sound levels are on the heavy side.

James Sampliner and four associates pump away at a rhythm-section accompaniment he arranged in association with the composer and Doug Varone supplied the unobtrusive choreography.

This show works better than might be expected. What it needs now is clarification as to what it all means.

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