Abstract: Disclosed are systems and methods for sleep analysis using an accelerometer-based user device. In one aspect, motion-based data from an accelerometer associated with the user device are used to determine one or more average normalized activity levels based on a series of consecutive motion-based data samples. An epoch decision value is determined using one or more consecutive normalized activity levels, and a sleep-decision window value is determined using a series of one or more consecutive epoch decision values. A sleep-state value is determined using the epoch values from the series of epoch values and is compared with reference sleep-state values to determine the sleep state of the user of the device. In some examples, the systems and methods may include a method for dynamically calibrating the data received from the accelerometer.