Flash led and heart rate monitor led integration and related devices and methods

A wrist-wearable device, comprising:

• a body, comprising:
• a front face and an opposite rear face, the front face including a display for displaying content to a user;
• an image sensor positioned in the rear face;
• a heart rate monitor sensor positioned in the rear face;
• and
• a light emitting diode positioned in the rear face and configured to provide a flash for the image sensor and to provide light for the heart rate monitor sensor;
• and
• a band configured to support the body on a wrist of the user.

A non-transitory computer-readable medium comprising one or more computer-executable instructions that, when executed by at least one processor of a computing device, cause the computing device to:

• determine, with a sensor, that a watch body is attached to a watch band, wherein the watch body includes a front surface and a rear surface that is configured to contact a user's wrist when the watch body is attached to the watch band and donned by the user;
• when the watch body is attached to the watch band, cause at least one light emitting diode on a rear surface of the watch body to emit light for a heart rate monitoring function of the watch body;
• determine, with the sensor, that the watch body is detached from the watch band;
• and
• when the watch body is detached from the watch band, cause the at least one light emitting diode on the rear surface of the watch body to emit light for an image sensor on the rear surface of the watch body.