There's a self-effacing charm to the semiautobiographical yarns of comedian Mike Birbiglia. He's a living contradiction, a charismatic nebbish. That's a good thing, because he is in practically every scene of "Sleepwalk With Me," and yet there's never too much of him. He's so comically appealing that you fear to look away from the screen even for a moment, in case you'll miss something.

Birbiglia has turned his true-life adventures as a commitment-fearing fiancé, a struggling standup comic and a sleep-disordered somnambulist into a best-selling book, off-Broadway play and popular monologues on public radio's "This American Life."

Onscreen, his anxious Everyschlub quality isn't tiresome, because somehow he's built a full range of emotional levels -- both comedy and drama -- into his low-key grumbling. He makes muddling through not a plot gimmick but a way of life.

Birbiglia, who also co-wrote and directs, plays Matt, a younger version of himself as he drifts through a period of early-adult anomie. He's a nightclub bartender engaged to a smart, beautiful voice teacher (Lauren Ambrose of "Six Feet Under"), but he doesn't want to marry "until I'm sure that nothing else good can happen in my life." His excuse is a bit pathetic; we can see that underachieving Matt feels unworthy.

Matt is not seeking love, or sex, or even a job, really. He's searching for independence from other people's expectations. He's in flight from his bossy physician dad (James Rebhorn) and cuckoo mom (Carol Kane) as well as his girlfriend and 9-to-5 life in general. He finds self-validation when he mumbles a few jokes into a microphone and persuades a dubious agent (deadpan Sondra James) to find him some standup gigs. "You're not funny, but the good news is that this business has nothing to do with funny," she says. The important thing is, he has access to his dad's car for out-of-town bookings.

Working small colleges and dive bars lets this naturally funny man's talent grow. His sort-of career gathers momentum, but so does his potentially dangerous sleep disruption. We find Matt fully dressed and showering at midnight, and traveling into oddball fantasies where he's fleeing jackals or winning a medal in the Dustbuster Olympics. Then he wakes to find himself out of bed and bewildered.

We're told that "to be a comedian you have to be a little delusional," but Matt's late-night rambles can put him in physical danger. His refusal to seek treatment frustrates his parents as much as his indecisiveness disappoints his girl. Birbiglia is bracingly honest and ruefully funny about Matt's refusal to take responsibility for his personal and professional missteps.

"Sleepwalk" is full of nice touches, from in-the-know cameos (comedian Marc Maron as a philosophical mentor, producer Ira Glass as a wedding photographer). It's a three-layered structure of straightforward narrative, surreal dream sequences and straight-to-camera soliloquies. Birbiglia's pleasingly nasal delivery and agreeable presence holds it together. Before one low point, he turns to the audience and confides, "Before I tell you this part of the story, I want to remind you that you're on my side." Yes, we are.

Colin Covert • 612-673-7186