Carly Rae Jepsen splits her eighth album Day and Night into two halves

Carly Rae Jepsen put out her eighth album on 18 September, and the structure is the first thing to know about it. Day and Night runs to 24 tracks across two clearly separated halves, which is less an indulgence than a change of habit.

The Day side is the one that sounds like her reputation: warm, breezy, synth-forward, leaning towards bedroom disco. Habits Of Creatures is the track WBUR's Amelia Mason picked out as typical of it when she talked the record through on NPR's All Things Considered.

The Night side is a dance record with thumping beats and darker production, built for a 2am floor rather than an afternoon. It opens with Never Let A Good Thing Die, a propulsive disco track whose bassline, Mason said, could almost pass for a genuine disco-era hit until a very electronic sample in the chorus gives the game away.

Since 2015's Emotion, Jepsen has followed every album with a companion collection of B-sides. Day and Night is the first time she has not waited: both halves arrive at once, and Mason's view is that none of these songs belong on a B-side at all.

Asked where to start, she went with Versailles, on the grounds that it captures something permanently true about Jepsen. She is very good at writing about yearning, and equally good at being self-aware about being a person who yearns. The lyric lists what the narrator wants in a row of contradictions, and the production does something genuinely surprising at the chorus, which Mason called rare in pop.

Jepsen arrived on the charts in 2012 with Call Me Maybe, still one of the best-selling singles ever released, and has spent more than a decade since making pop records that reviewers like more than the charts do. No tour or single plans were announced alongside this one. Her other current project is the stage musical of 10 Things I Hate About You with Lena Dunham, which has a Broadway date after being announced earlier this year. Day and Night sits between pop and electronic on the release calendar.