A thermostat may include a memory and a processing system. The processing system may operate by determining a set of wake-up conditions for the processor to enter into a second operating state from a first operating state, the set of wake-up conditions including at least one threshold value associated with at least one environmental and/or time-of-day condition; causing the set of wake-up conditions to be stored in a memory; operating in a first mode in which the processor is in the first operating state during a time interval subsequent to causing the set of wake-up conditions to be stored in the memory; determining, while the processor is in the first operating state, whether at least one of the set of wake-up conditions has been met; and then operating in a second mode in which the processor is in the second operating state.