A wearable device in one embodiment includes a motion detection sensor, an alarm clock and a sleep monitor operatively coupled to the motion detection sensor and the alarm clock. The sleep monitor monitors a person during sleep by collecting motion detection sensor data at a first data collection rate and determines a sleep state of the person based on the collected motion detection sensor data at the first data collection rate. If the sleep monitor detects that the alarm clock has entered a snooze mode, then the first data collection rate is increased to a second data collection rate and motion detection sensor data is collected at the second data collection rate while the alarm clock system in the snooze mode.