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Pre-alarm is a feature that plays a quiet alarm before your main alarm, helping you wake up more naturally and gently. This gives your body time to transition from deep sleep before the main alarm sounds.

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How it works

When pre-alarm is enabled for an alarm:
  1. A quiet alarm plays at a reduced volume 30 minutes before your scheduled alarm time (by default)
  2. The pre-alarm gradually fades in, just like the main alarm
  3. The pre-alarm volume is set to half of the configured pre-alarm volume setting
  4. If you don’t respond to the pre-alarm, the main alarm will sound at the scheduled time
Pre-alarm uses the same alarm tone as your main alarm, but at a significantly reduced volume to wake you gently.

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Configuring pre-alarm

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Global settings

You can configure the default pre-alarm behavior in Settings:
Preference key: prealarm_duration
Default value: 30 minutesThis controls how many minutes before the main alarm the pre-alarm will sound. You can set this to:
  • -1 to disable pre-alarm globally
  • Any positive integer for the number of minutes before the main alarm
Preference key: key_prealarm_volume
Default value: 5 (out of 10)
Maximum value: 10This controls the volume of the pre-alarm. The actual volume is calculated as:
  • Pre-alarm volume setting × 0.5 (half of the selected level)
  • This is then gradually faded in over the fade-in duration

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Per-alarm settings

Each alarm has its own pre-alarm toggle in the alarm details screen:
  1. Open an alarm’s details
  2. Find the “Pre-alarm” checkbox
  3. Enable or disable pre-alarm for that specific alarm
If the global pre-alarm duration is set to “none” (-1), the pre-alarm option will not appear in individual alarm settings.

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Pre-alarm behavior

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Snoozing pre-alarm

When a pre-alarm is playing, you can:
  • Snooze normally: The pre-alarm will snooze and play again after the snooze duration
  • Snooze to a specific time: If you snooze to a time, the alarm transitions to the snoozed state instead of pre-alarm snoozed

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Dismissing pre-alarm

If you dismiss a pre-alarm, the main alarm will still sound at its scheduled time. The pre-alarm only serves as a gentle warning.

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Timeout behavior

If the pre-alarm is not acknowledged:
  • Auto-silence will apply if enabled
  • The main alarm will still fire at the scheduled time
Pre-alarm scheduling is intelligent: if you set an alarm with less time remaining than the pre-alarm duration, only the main alarm will sound. For example, if you set an alarm 20 minutes from now and pre-alarm is set to 30 minutes, the pre-alarm will be skipped.

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Technical details

For developers and advanced users:
  • Pre-alarm state is stored in AlarmValue.isPrealarm (source: AlarmValue.kt:28)
  • The pre-alarm offset is calculated in milliseconds: preAlarmDuration * 60 * 1000 (source: AlarmsScheduler.kt:147)
  • Pre-alarm uses dedicated states in the alarm state machine: PreAlarmSetState, PreAlarmFiredState, and PreAlarmSnoozedState

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Use cases

Light sleepers

If you wake easily, pre-alarm gives you a heads-up before the main alarm

Heavy sleepers

Start the waking process earlier with a gentle sound

Important appointments

Extra insurance that you’ll wake up on time

Gradual transition

Wake up from deep sleep more naturally

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