Happy as queen of sad

For someone who spends as much time as Sarah McLachlan does ricocheting off the rocky walls in the house of pain, she sure smiles a lot.

After a two-hour tour through an emotional terrain next to which Joseph Conrad’s “Heart of Darkness” can seem like a cruise through Disneyland, the Canadian singer-songwriter thanked Tuesday’s half-capacity crowd at the Arrowhead Pond in Anaheim for such a “fun” evening, adding “it makes me so happy.”

Makes you wonder what it would take to get her down.

In fact, she recognizes and even revels in her place as “the queen of the sad, depressing love song,” as she put it at one point in a beautifully designed show that carried more instrumental and tonal colors than emotional variation.

Much of it leaned on her latest album, “Afterglow,” a work mostly surveying relationships and romantic illusions that wind up shattered like so many glass shards on a kitchen table that’s been upended. Given that, the title seems to suggest more the eerie illumination that follows a nuclear blast than the warm fuzzies of a woman who’s returned to the spotlight after giving birth to her first child.

The predominantly female audience she nurtured during her years running the woman-centered Lilith Fair festival devours each expression of hurt, disappointment, anger and, occasionally, joy. And it’s not as if they haven’t been warned. As she sang in “Hold On,” a 1994 song that could serve as the fair warning label for her entire career: “Hold on to yourself, because this is going to hurt like hell.”

McLachlan’s weapon as a songwriter is her knowledge that more relationships fail than succeed, and that the former territory is much richer fodder for artistic exploration. Unlike a Lucinda Williams who creates a palpable sense of time, place and character, McLachlan prefers to work in a timeless realm, one reflected in the set that evoked an ancient Celtic meeting place.

That takes the listener directly into the raw recesses of her heart, and over the course of two hours it can take on the feeling of an extended therapy session. That smile of hers, however, periodically signaled that all is not lost and helped balance the scales, as did her rare forays into the lighter shades of life.

“I never thought I could write a love song that ended happily,” the 36-year-old musician said with a chuckle before singing “Push,” a straightforward ode to her husband Ashwin Sood, also the drummer in her tasteful and resourceful six-member band.

Because of the contrast with the struggle that’s preceded it, “Push” came through as a hard-won victory on the field of love. To reassure fans that her new life as a mom hasn’t been as thorny as the evening might have sounded, she noted that she wrote most of the songs on “Afterglow” before her baby came.

The evening’s material coursed through the catalog she’s built up in the 15 years since her debut album, “Touch,” added a striking voice to the singer-songwriter genre. That voice stays mostly in a dark, alto range, but hops frequently into falsetto in a way that embodies the emotional leaps and bounds her lyrics describe.

She and her band, who were also due at Staples Center on Wednesday, moved comfortably from big-band arrangements with a U2-like sense of atmosphere to stripped down partial-band segments and solo moments in which she accompanied herself on guitar or piano, making for a rewardingly well-rounded show.

It’s likely she’ll have some brighter things to discuss down the line, but more likely McLachlan won’t ever turn her back fully on the dark and painful path she’s explored so thoroughly and successfully.