Wake-up alarm method

An electronic device, comprising:

• an optical sensor;
• and
• a controller, adapted to implement a wake-up alarm function on the electronic device, and wherein the controller is adapted to, following activation of an alarm signal triggered by the wake-up alarm function:
• monitor a sensed light input at the optical sensor;
• cease the alarm signal responsive to detecting occurrence of one or more cessation criteria, the one or more cessation criteria including at least:
• detecting that a light intensity or illuminance of the light input exceeds a first pre-determined threshold, and/or that an amount of light flux detected since the alarm signal activation exceeds a first pre-determined threshold, and
• following said cessation of the alarm signal, monitor the light input at the optical sensor and re-activate the alarm signal dependent upon occurrence of one or more reactivation criteria, the reactivation criteria including at least:
• detection of a fall in the intensity or illuminance of the light input below a second pre-determined threshold within a pre-defined time window following the alarm signal cessation.