Brooklyn outfits the Epochs and the Big Sleep have little in common aside from their home borough. The Epochs trade in beat-happy electronic indie-pop, while the Big Sleep is a hair-parting power trio. But both release their sophomore albums today, and both records — the Epochs’s self-titled debut on the Rebel Group and the Big Sleep’s “Sleep Forever” on Frenchkiss — capture bands not only finding their songwriting strengths, but ascending from the underground.

The Epochs is the more instantly pop friendly of the two bands. Brothers Hays Holladay (guitar and vocals) and Ryan Holladay (keys-vocals) emerged as the Epochs with their 2003 self-release “Ten Billion Light Years of Solitude.” Bassist Kevin Smith and drummer Kotchy have since beefed the group up to a four-piece, and it’s a lithe and responsive quartet, as evidenced on “Thunder and Lightning,” the opening track of the new album. A flash of bass and drums backs a choppy guitar filigree that introduces the song, whose stormy sound echoes its apoplectic desires: “I’m weak I cannot stand / but I’d give my arm to have her hand,” Hays seethes in the second verse.

“Thunder and Lightning” is a canny bit of misdirection, though, as what follows on “The Epochs” is much more orchestral, atmospheric, and electronic than the fairly generic rock of the opener. The 10 songs that follow offer the group’s best songwriting ideas, molding a penchant for dance-music melodies, indie-pop’s sunny optimism, and a pop ear for simple love songs into a tasty streak of catchy tunes.

Don’t read “simple” as ordinary or naïve, though. The smartest thing the Epochs do is keep their arrangements tight, their melodies spacious, their beats visceral, and their production trim. Far too many ambitious electronic and rock hybrid bands overstuff their tracks with clutter just because they can — TV on the Radio comes to mind. The Epochs stick to more elemental, Postal Service-like production to complement their winsome vibes.

And so the Taser-like synthesizer stabs and cascading keyboard lines of “Opposite Sides” don’t drown out the vocal harmonizing on the song’s Brian Wilsonesque chorus. The gently skipping drums and synthesizer duo that sketches the jaunty pulse to “Right On” sets up the song’s bipolar jumps between acoustic, guitar-backed verses and the percussive chorus. And “Mouths To Feed” is powered by just a wispy electronic flutter and keyboard tickle until the drums explode into the chorus. “The Epochs” is an indie-pop album smart enough to borrow just enough electronic trickery and rock oomph.

Sonically, the Epochs sound very similar to Bloc Party, only thankfully not cursed with that Radiohead malaise of trying to describe the postmodern human condition with every breath. And the Epochs are a better band thanks to such modesty. Standout track “Love Complete” spices a heartbeat drum pace and singsong keyboard line with hand-clap accents and a string arrangement, yielding a song of Psychedelic Furs-caliber bittersweet pop. The song won’t offer any intellectual armature to fight the existential blues, but it sure feels good to be alive during its four minutes.

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By contrast, the Big Sleep is quite simply a great rock band. Fronted by the husband-wife wallop of vocalist-guitarist Danny Barria and bassist-vocalist Sonya Balchandani, and backed by hammering drummer Gabriel Rhodes, the Big Sleep has miraculously found a way to capture the super-fuzz smoke emanating off late-1960s psych rock and distill it into the heady, swirling bliss of space-rock density. Yes, the Big Sleep is the love child of Blue Cheer and My Bloody Valentine, and anybody who has ever caught the trio live knows the band more than lives up to that billing.

“Sleep Forever,” like the trio’s 2006 debut, “Son of the Tiger,” is primarily instrumental. But where “Tiger” tended toward the plodding and introspective, “Forever” is propulsive and robust. Mr. Barria hasn’t changed his guitar tone much — he may have the most instantly recognizable guitar sound this side of Mudhoney’s Steve Turner — but the band seems to have expanded around him. Where Mr. Rhodes and Ms. Balchandani were often content to find extended grooves behind Mr. Barria’s guitar on past projects, here they both want to be part of the ruckus.

The result is noisy, seductive accessibility. On instrumentals such as “Slow Race,” “The Big Guns,” and the flabbergasting “Undying Love,” the Big Sleep forge quavering, anthem-like rods of rippling rock steel. “Undying Love,” especially, is superb instrumental rock, a heavy and dynamic statement that puts the Big Sleep in the same realm of baroquely expressive wordless rock as the Japanese metal outfit Boris.

The trio pulls an ace out of its sleeve every time Ms. Balchandani sings, though. She doesn’t have the nimblest of voices — in fact, it’s a rather flat, mid-range monotone. But she uses that glassy-eyed presence to sublime effect on tracks such as the threatening “Bad Blood” and the heroic “Tigers.” She almost deadpans “there’s trouble in my house” and “there’s a stranger at my door” during the chorus of “Bad Blood,” and her delivery creates a delicious friction between the lyric’s immediate peril and her ordering-a-cheeseburger attitude.

“Sleep Forever” is rife with such moments and many other surprising juxtapositions, from the lovely acoustic guitar of “Little Sister” that feels disarming after the paisley throttle of “Pinkies,” to the electronic pulse that kicks off the melancholic “Chorus of Guitars.” An acoustic guitar and a drum machine are mere adornment on the Big Sleep’s core of bass, drums, and electric guitar, and the potential energy promised by those weapons constantly hovers somewhere in the album’s mix. That the band doesn’t always feel the need to mess up a great, thundering song with words makes “Sleep Forever” one of the most solid no-filler rock records of this young year.

The Big Sleep plays a record release show at the Mercury Lounge on Thursday.