Techniques for Using Inward-Facing Eye-Tracking Cameras of a Head-Worn Device To Measure Heart Rate, and Systems and Methods Using Those Techniques

The various implementations described herein include methods and systems for monitoring biometric information. In one aspect, a method includes (i) capturing, via an inward-facing camera of an artificial-reality headset, a plurality of images of a region of a face of the user, the region including an eye of the user, where (a) a first image of the plurality of images includes a first position of a pupil in the eye, and (b) a second image of the plurality of images includes a second position of the pupil in the eye, the second position different than the first position; and (ii) determining heart rate information based on the plurality of images.