This disclosure provides systems and methods for detecting a change in environmental conditions utilizing sampling circuitry configured to sample an environmental sensor while a processor remains in a low-power state or a sleep state. According to some embodiments, a pre-filter performs a simplified analysis of the sensor samples to determine if the processor should wake and perform additional analysis on stored sensor samples. Specific examples are provided for detecting motion using passive infrared detectors. Accordingly, systems and methods for reducing the power consumption of a motion detection system are provided herein.