How it works

The rhythm

Voco is built around a simple rhythm: study before you sleep, then quiz yourself after you wake.

Nothing is locked by the clock. You can study and quiz at any hour; the time of day only changes what the home screen suggests.

Why sleep

Sleep helps stabilize and strengthen memories formed while you're awake, a process called memory consolidation. One important part of this is replay: during sleep, the hippocampus (central to forming new memories) and the cortex replay recent experiences together, which helps make those memories more stable and long-lasting. Studying shortly before bed gives that process fresh material to work on. Quizzing yourself afterward (pulling words back out rather than rereading them) strengthens them further.

The research on sleep and memory is well established, though how much it helps varies from person to person; think of it as a helpful rhythm, not a guarantee.

Why the colors change

The colors follow the actual time of day, wherever you are in the app: deep night blues in the evening and warm dawn tones in the morning, whichever screen you're on. The home screen also shifts gently with your local time. Evenings point you to tonight's study, and mornings bring back last night's words.

Streaks

There are two. The flame counts the days you completed any quiz. The sunrise is your night-to-morning streak: consecutive mornings you quizzed the words you studied the night before. Tap either one on the home screen to share it as an image.