# Dismiss an alarm with light

URL: https://clock.adrianillo.name/manual/en/light/
Clock: https://clock.adrianillo.name/en/
Functional review: 2026-11-10
Reference version: 1.3.1
This manual describes the reviewed project; the version available on Google Play may differ.

Enable detection and calibrate where you will place the phone.

## Enable the light action

1. Check that your phone has a light sensor. Open the alarm editor and enable light detection.
2. Choose whether a light change will dismiss or snooze the alert. Adjust that alarm's sensitivity and save.
3. Place the phone in its usual position with the sensor uncovered and test an alarm with the room light off. Then switch the room light on and check the action.

Keep in mind: Detection depends on ambient light, sensor and placement. Test it before relying on it to wake you.

![Light sensitivity and actions for light or shaking](https://clock.adrianillo.name/manual/assets/screenshots/en/alarm-actions--dark.png)
[View light theme](https://clock.adrianillo.name/manual/assets/screenshots/en/alarm-actions--light.png)

## Auto-calibrate sensitivity

Confirmation applies the profile to existing and new alarms. You can then select a different sensitivity for an individual alarm. Moving the global slider without applying does not save the change.

1. Open Settings, find Light detection sensitivity and tap Auto-calibrate.
2. Put the phone where it will be during the alarm. Turn the light off, keep it still and tap Measure with light off.
3. Turn the light on without moving the phone and start the second measurement.
4. Review the suggested sensitivity. Adjust the slider if needed, then confirm Set and apply to all.

![First measurement: keep the phone still with the light off](https://clock.adrianillo.name/manual/assets/screenshots/en/calibration-dark--dark.png)
[View light theme](https://clock.adrianillo.name/manual/assets/screenshots/en/calibration-dark--light.png)

![Second measurement: turn the light on without moving the phone](https://clock.adrianillo.name/manual/assets/screenshots/en/calibration-bright--dark.png)
[View light theme](https://clock.adrianillo.name/manual/assets/screenshots/en/calibration-bright--light.png)

![Review the suggested sensitivity and adjust the slider if needed](https://clock.adrianillo.name/manual/assets/screenshots/en/calibration-result--dark.png)
[View light theme](https://clock.adrianillo.name/manual/assets/screenshots/en/calibration-result--light.png)

![Confirm applying to existing and new alarms](https://clock.adrianillo.name/manual/assets/screenshots/en/calibration-confirm--dark.png)
[View light theme](https://clock.adrianillo.name/manual/assets/screenshots/en/calibration-confirm--light.png)

## If it stops too early or does not respond

Reduce sensitivity if the screen or another weak light is enough to dismiss it. Increase sensitivity if the room light does not trigger the action, first checking the sensor is uncovered.

If readings are unstable or the light increase is too small, repeat calibration. A failed or cancelled measurement keeps the previous settings. Without a compatible sensor, use the screen buttons or another available action.