One dial. Sound all night.

Traffic, a restless partner, a room that is never quite quiet. Thirteen sounds, layered up to four at a time.

Seven are generated in real time — white, pink, brown and green noise, a fan, an air conditioner and an airplane cabin, built sample by sample for as long as you play them. There is no file underneath, which is why they never settle into the short, obvious loop you eventually stop being able to un-hear.

Six are real field recordings — waves on rocks, ocean, gentle rain, night crickets, morning birds, a dawn chorus. These are finite files and they do loop; the app tells you how long each loop is rather than pretending otherwise, and they are mastered to the same loudness as the generated sounds, so bringing one into a mix never makes it lurch.

Stack up to four sounds. Tap any one to set its volume, tone and swell live while the rest keep playing; hold it to solo it.

Auditioning a sound in the library never disturbs the mix you already have — it comes right back when you close the sheet.

Rate the night on a four-point scale and get on with your day.

After a week there is enough signal to name the mix you actually sleep best with, and the card says so in one line — never as a score, never as a streak.