'Up All Night' with a sitcom baby

THE SHOW "Up All Night:

WHEN | WHERE Wednesday night at 10 at NBC (repeats tomorrow at 8:30 and Saturday at 9 p.m.). Then airs Wednesdays at 8 p.m.

REASON TO WATCH Having a baby changes your life. (Empathy scream here.)

WHAT IT'S ABOUT Christina Applegate and Will Arnett give up their wild Hollywood eating-drinking-dancing-smoking lifestyle to have a baby. Then, she goes back to work producing an "Oprah"-style TV show, while he plays "baby daddy," which, by his definition, means staying home raising the kid.

How hard could it be? She's torn between family time and executing show themes like "eats for the diabeets." He gets spooked by baby-loving old ladies in scary-huge supermarkets, when he isn't playing video games with some surfer daddy dude from the park.

In other words: They're overwhelmed.

MY SAY But, thank goodness, their show isn't. NBC's original pilot provided to critics in the spring was a music-pumped, digression-crammed mess, committing the cardinal sin of bearing little resemblance to Real Life.

The do-over premiering tonight has chilled out considerably, putting the focus on what truly matters -- family -- to anybody who is now or ever has been in our stars' situation. The single-camera tone is less showoff-y, more forgiving and appreciably sweeter, while still retaining a hip wistfulness for those crazy days before 24/7 baby maintenance and nurturing.

"Up All Night" has grown up, stepping outside its self-absorbed Hollywood head and into the heart-land where even outre characters like the TV diva played by Maya Rudolph ("Saturday Night Live") should be made likable while egotistically talking in funny accents. She, Arnett and especially the sublime Applegate now sell it well by not trying to.

BOTTOM LINE A well-rounded, nicely mature comedy.

GRADE B