It’s an endless cycle, good for maybe a minute of entertainment before you go back to reading the newspaper, or buffing your nails, or chatting up the person next to you who’s also bored with watching laundry.

Television is like that.

Here come those reality shows that had you gagging at the thought of eating live worms a year ago. Here come the medical shows that used to make you think that maybe your pancreas was rotting or you had a brain tumor, when all that was really wrong was you’d been drinking too much Starbucks. There go the game shows that convinced you that you were smarter than those yahoos who couldn’t get the answers right even with a lifeline and a complete set of the Encyclopedia Britannica at hand. There go the Westerns that used to make you think life would have been simpler, better, in Montana in the 1890s, until you realized that people didn’t bathe much back then and that it got really, really cold in Montana in the winter.

Like your clothes in the little window in the dryer at the Laundromat, television cycles endlessly.

One of the more interesting genres that’s flashing by the window of our TV sets again this season is the family sitcom. Nuclear families caught up in the throes — and the humor — of child rearing are emerging center-stage from the endless cycle. The critics don’t particularly care for them, but younger viewers are discovering them. And advertisers love them.

They’re not the harder-edged or sassy comedies of recent times, like “Married … With Children” or “Roseanne.” They’re more like “My Three Sons” and “The Danny Thomas Show.” But they’re updated for the new millennium, and the scripts are better.

Maybe it’s a post-9/11 thing. Or maybe viewers have had enough of heebie-jeebie double-rich chocolate with cookie-dough swirls and are rediscovering the sweet simplicity of plain vanilla. Or maybe it’s both.

Whatever the reason, old-fashioned half-hour comedies are making a comeback, as evidenced by the early success of “Life With Bonnie,” “Still Standing,” “Hidden Hills” and “8 Simple Rules for Dating My Teenage Daughter.”

If you won’t believe it until you see it with your own eyes, check out “8 Simple Rules.” It’s one of the best of the new-old breed. It stars John Ritter — and who knew that Ritter still had it in him? — as Paul, a perfectly competent, rational dad who suddenly discovers his two loveable daughters have become hormonally controlled creatures who speak another language entirely. Katey Sagal (“Married … With Children”) co-stars as his wife, Cate, with Kaley Cuoco as his 16-year-old, Bridget, and Amy Davidson as his 15-year-old, Kerry. There’s also a 13-year-old son, Rory (Martin Spanjers), who’s behaving himself for now.

Cate has gone back to work as a hospital nurse, but Paul is a sportswriter, so he works at home a lot and can keep track of the kids.

Of the eight rules in the show’s title, the major one in Paul’s mind is this: If you make my daughters cry, I’ll make you cry. Neither Steve Douglas or Danny Williams would ever have said such a thing, but hey, it’s the new millennium, and even a plain-vanilla sitcom has to have a kick to it now.

Based on W. Bruce Cameron’s best-selling book by the same title, “8 Simple Rules” is a fun sitcom with an air of realism, one that viewers can almost picture being a part of. And it sure beats scarfing down worms or getting frostbite in Montana. S

“8 Simple Rules” airs Tuesday nights at 8 on ABC-TV.