Enable the light action

Check that your phone has a light sensor. Open the alarm editor and enable light detection.
Choose whether a light change will dismiss or snooze the alert. Adjust that alarm's sensitivity and save.
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.

Clock — Light sensitivity and actions for light or shaking (en) — Light sensitivity and actions for light or shakingReal screenshot with sample data. Tap the image to see it in full.View light theme View dark theme

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.

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

Clock — First measurement: keep the phone still with the light off (en) — First measurement: keep the phone still with the light offReal screenshot with sample data. Tap the image to see it in full.View light theme View dark theme

Clock — Second measurement: turn the light on without moving the phone (en) — Second measurement: turn the light on without moving the phoneReal screenshot with sample data. Tap the image to see it in full.View light theme View dark theme

Clock — Review the suggested sensitivity and adjust the slider if needed (en) — Review the suggested sensitivity and adjust the slider if neededReal screenshot with sample data. Tap the image to see it in full.View light theme View dark theme

Clock — Confirm applying to existing and new alarms (en) — Confirm applying to existing and new alarmsReal screenshot with sample data. Tap the image to see it in full.View light theme View dark theme

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.