The light from Laura Zigman’s new novel, “Separation Anxiety,” is generated by a kind of literary nuclear fusion: an intense compression of grief and humor. The combination of those elements usually produces cynical black comedy, something witty and bitter, but Zigman’s work is too tender for that.

“Separation Anxiety” is a long-awaited comeback for this clever writer who hasn’t published a novel since “Piece of Work” in 2006. A series of personal tragedies, including the deaths of her parents and her own cancer diagnosis, swept Zigman into what she calls “so many dormant years.” But now, she’s transmuted those struggles into a new book — a “second chance” — about a once-successful author whose world is collapsing under the weight of disappointment and fear.

When we meet the narrator, Judy Vogel, she’s been deflated by a steady leakage of optimism. Years earlier, she had published a classic children’s book that became a PBS series — a thrilling, lucrative success that led to exactly nothing else. At 50, she’s mourning the loss of her parents, nursing her best friend through the final stages of a deadly illness and longing for the happy rapport she once enjoyed with her son, who has drifted into “brutal teenage opacity.”

What’s worse, Judy is trapped in a zombie marriage. It’s over between her and her husband, but he can’t afford to live anywhere else, so he’s sleeping in the guest room, and they’re lumbering along, pretending everything is fine.

Everything is not fine.

“Life eventually takes away everyone and everything we love and leaves us bereft,” Judy says at her lowest point. Clutching a copy of Marie Kondo’s best-selling decluttering book, she goes down to the basement in a last-ditch effort to find sparks of joy. “So little gives me joy now that I’m afraid I’ll get rid of every single thing I’ve ever owned and end up with nothing,” she admits. “Feeling empty only makes me want to be emptier.”

In these opening pages, Zigman digs into the self-confirming nature of depression with the authenticity of someone who’s been hounded by that black dog. But the sorrow here is always twined with comedy. Amid all the basement junk, Judy finds an eco-friendly baby sling that she never used. Impelled by longing, she puts it on. “I feel like Björk at the Oscars wearing that swan,” she says, but something’s missing. She tries filling the sling with bath towels. Then a cabbage. Finally, it strikes her: The family dog, Charlotte, is just right. “At first, I only wear the dog inside the house,” she says. “It seems harmless enough. An improvised self-care remedy that instantly works better than any psychopharmaceutical or baked good ever has.”

That deliciously absurd tone runs straight through this novel. Soon Judy is wearing her 20-pound dog-baby to the grocery store and even to her son’s school. “Shouldn’t everyone be wearing a dog for improved mental health?” she wonders.

But what keeps “Separation Anxiety” from spinning off into some surreal parallel universe of silliness is Zigman’s attention to the ordinary absurdities of middle-class life. She has a great humorist’s eye for the comedy we’ve seen but overlooked — such as the strained preciousness of Montessori schools or the self-satisfaction of people who subscribe to meal kits. She’s particularly witty about the vapidity of our self-help culture. To make ends meet, Judy churns out click-bait for a healthyish website called Well/er, e.g. When accepting failure is a Good Thing; Does working at home make you less attractive? (If you’re one of the “lucky” people still working as a journalist, this too-real line of contemporary satire will make you laugh . . . and cry.) And one of the novel’s funniest sections involves an Instagram guru “in leggings and a white cashmere poncho-cape” whose perfectly curated life is the object of Judy’s jealousy and derision. (Gwyneth Paltrow: Call your agent — or your lawyer.)

Perhaps the most admirable aspect of “Separation Anxiety” is the way Zigman subtly choreographs the novel’s apparently random goofiness. The life-size puppet performers who move into Judy’s house even as her marriage collapses would seem to stretch the antics too far. “My moms were founding members of this puppet theater at Bennington College,” one of them explains. “They just did a puppet adaptation of The Vagina Monologues.” But those “Puppet People” end up making perfect sense and a salutary contribution to Judy’s home. Same with a dark, scatological subplot at her son’s school. For better or worse, poop happens. Judy can learn to deal with it or let it overwhelm her.

Stalked by the loneliness of middle age, you may think the last thing you need is a novel about a woman driven to wearing her dog. You’d be wrong.

Ron Charles writes about books for The Washington Post and hosts TotallyHipVideoBookReview.com.

Separation Anxiety

By Laura Zigman

Ecco. 276 pp. $26.99