System and method for measuring physiologically relevant motion

A system for identifying a physiologically relevant biorhythm of a subject, comprising:

• at least a motion sensor configured to sense movement of a first body part of the subject and configured to measure micromovement of the subject and produce a time series of micromovement data representing the micromovement of the subject over a period of time, wherein the micromovement is movement at or below a millisecond and millimeter scale;
• at least a biometric sensor attachable to a second body part of the subject and configured to measure simultaneously a non-motion biometric of the subject and produce a time series of biometric values of the subject over the period of time;
• a processing device;
• and
• a computer readable medium containing programming instructions that, when executed, will cause the processing device to:
• determine a noise-to-signal ratio based on the time series of micromovement data for each of a plurality of time intervals within the period of time and for each of a plurality of ranges of values of the biometric in the time series of biometric values, and
• identify as a physiologically relevant biorhythm at least a portion of the time series of micromovement data, wherein the portion is defined by at least one range of the plurality of ranges of values for the biometric and at least one time interval of the plurality of time intervals, and the noise-to-signal ratio determined for the portion is lower than 50% of all the noise-to-signal ratios determined.