Select Menu > Ctrl. panel > Settings > General > Personalization > Notification lights.
When you miss a call or receive a message, the scroll key starts blinking to indicate the event. To set the blinking time and which events you want to be notified, select Notification light.
When you do not use the device for a certain period of time, the scroll key starts blinking slowly as if it was breathing. To turn the breathing light on or off, select Standby br.light > Breathing light.