A method for an alarm silencing or suppression routine following activation of a wake-up alarm on an electronic device (42). The method comprises, following the alarm activation, monitoring (14) light levels at a light sensor (44) of the device and automatically silencing (20) or otherwise suppressing the alarm signal responsive to sensing (16) a light level at the sensor above a pre-defined threshold. Following alarm signal suppression, a further confirmatory monitoring period follows in which light levels at the sensor continue to be monitored (22). If they fall to below a further predefined threshold (26), or below the original silencing threshold, the alarm signal is reactivated (28). This ensures that a user has not returned to a darkened environment a short space of time after alarm silencing, which might lead to the user falling back to sleep.