Hang up those dancing shoes and pull out those headphones: On her eighth album, “Anti,’’ Rihanna abandons the dance-floor in favor of a late-night, post-club vibe session.

When the long-gestating 13-track collection was apparently accidentally leaked on Wednesday, after months of buzz-building by the Barbadian performer, the streaming service Tidal made the entire album available, and fans got a sense of at least one reading of the title. (Rihanna is signed to the label and management company of Tidal principal Jay Z.)

While “Anti’’ is certainly not the complete opposite of what Rihanna has done in the past, it does veer away significantly from the glinting, hard pop polish of previous efforts, and finds her offering up some of the moodiest and, in a few cases, most traditionally soulful songs of her career.

She begins in an unsettled mood on “Consideration,’’ seeking peace of mind over a crunchy groove and a stutter-step beat, and then descends into the weed-smoke haze of the interlude “James Joint.’’ From there, the tempos are conspicuously sluggish, the atmosphere gauzy. A rippling guitar underscores lusty but low-key entreaties to keep her up all night on “Kiss It Better,’’ before the singer-songwriter oozes into a woozy, repetitive pas de deux with Drake on the single “Work.’’

But a curious thing happens as “Anti’’ unfurls. Rihanna pivots from an expansive, murmury cover of Tame Impala’s languid, resigned “New Person, Same Old Mistakes’’ — here dubbed “Same Ol’ Mistakes’’ — into an old-school soul R&B vibe far less cluttered than what has preceded it.

The transformation begins with the comparatively unfussy acoustic-guitar ballad “Never Ending,’’ with Rihanna musing on romantic dissolution and its lasting tendrils. The real revelation comes next with “Love on the Brain,’’ as she deploys her infrequently used head voice over a classic slow soul groove, which makes the downshift into her familiar husky register that much more effective. As she implores “Don’t you stop loving me,’’ her performance has a grit, sweat, and weariness to it that’s unusual and humanizing. “Higher’’ continues the retro theme; while it feels more shrill and shouty vocally, it also feels fully engaged. Rihanna brings the proceedings to a close with a melancholy piano ballad, “Close to You.’’

With its sense of unease, quiet, and longing, much of “Anti’’ is unlikely to grab ears on first listen or play well to Rihanna’s broadest base of fans. (They’ll also need to look elsewhere for the trio of songs she released in 2015: “American Oxygen,’’ “Bitch Better Have My Money,’’ and the Kanye West-Paul McCartney collaboration “FourFive Seconds.’’) But it is an interesting artistic curveball in her heretofore hits-driven career.

ESSENTIAL “Love on the Brain’’

Rihanna plays the TD Garden on April 10.

Sarah Rodman can be reached at srodman@globe.com.